diff --git a/qa/rpc-tests/bip65-cltv-p2p.py b/qa/rpc-tests/bip65-cltv-p2p.py
index cfd2df01e..3daff0a37 100755
--- a/qa/rpc-tests/bip65-cltv-p2p.py
+++ b/qa/rpc-tests/bip65-cltv-p2p.py
@@ -1,9 +1,11 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 #
 # Distributed under the MIT/X11 software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import ComparisonTestFramework
 from test_framework.util import start_nodes
 from test_framework.mininode import CTransaction, NetworkThread
diff --git a/qa/rpc-tests/bipdersig-p2p.py b/qa/rpc-tests/bipdersig-p2p.py
index f254843f1..163933ab0 100755
--- a/qa/rpc-tests/bipdersig-p2p.py
+++ b/qa/rpc-tests/bipdersig-p2p.py
@@ -1,9 +1,11 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 #
 # Distributed under the MIT/X11 software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import ComparisonTestFramework
 from test_framework.util import start_nodes
 from test_framework.mininode import CTransaction, NetworkThread
diff --git a/qa/rpc-tests/blockchain.py b/qa/rpc-tests/blockchain.py
index c37db8b84..22dd299ec 100755
--- a/qa/rpc-tests/blockchain.py
+++ b/qa/rpc-tests/blockchain.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -8,6 +8,8 @@
 # rpc/blockchain.cpp.
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 import decimal
 
 from test_framework.test_framework import BitcoinTestFramework
diff --git a/qa/rpc-tests/decodescript.py b/qa/rpc-tests/decodescript.py
index 293fd0ebb..ea4916b06 100755
--- a/qa/rpc-tests/decodescript.py
+++ b/qa/rpc-tests/decodescript.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2015 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, initialize_chain_clean, \
     start_nodes
diff --git a/qa/rpc-tests/disablewallet.py b/qa/rpc-tests/disablewallet.py
index 339c6a8f6..e43a9519f 100755
--- a/qa/rpc-tests/disablewallet.py
+++ b/qa/rpc-tests/disablewallet.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # Exercise API with -disablewallet.
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import initialize_chain_clean, start_nodes
 
diff --git a/qa/rpc-tests/finalsaplingroot.py b/qa/rpc-tests/finalsaplingroot.py
index 1842ef7dc..59b184f03 100755
--- a/qa/rpc-tests/finalsaplingroot.py
+++ b/qa/rpc-tests/finalsaplingroot.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_equal,
diff --git a/qa/rpc-tests/forknotify.py b/qa/rpc-tests/forknotify.py
index 1be750a64..4386f246d 100755
--- a/qa/rpc-tests/forknotify.py
+++ b/qa/rpc-tests/forknotify.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # Test -alertnotify 
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import start_node, connect_nodes
 
diff --git a/qa/rpc-tests/fundrawtransaction.py b/qa/rpc-tests/fundrawtransaction.py
index 42896be4f..3b2535c73 100755
--- a/qa/rpc-tests/fundrawtransaction.py
+++ b/qa/rpc-tests/fundrawtransaction.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import assert_equal, assert_greater_than, \
diff --git a/qa/rpc-tests/getblocktemplate.py b/qa/rpc-tests/getblocktemplate.py
index af050110e..96fd73083 100755
--- a/qa/rpc-tests/getblocktemplate.py
+++ b/qa/rpc-tests/getblocktemplate.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2016 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, connect_nodes_bi, \
     initialize_chain_clean, start_nodes
diff --git a/qa/rpc-tests/getblocktemplate_longpoll.py b/qa/rpc-tests/getblocktemplate_longpoll.py
index 37a40384b..748c547e5 100755
--- a/qa/rpc-tests/getblocktemplate_longpoll.py
+++ b/qa/rpc-tests/getblocktemplate_longpoll.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import AuthServiceProxy
 from test_framework.util import random_transaction
diff --git a/qa/rpc-tests/getblocktemplate_proposals.py b/qa/rpc-tests/getblocktemplate_proposals.py
index 16b2e9b94..771e8b091 100755
--- a/qa/rpc-tests/getblocktemplate_proposals.py
+++ b/qa/rpc-tests/getblocktemplate_proposals.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 
diff --git a/qa/rpc-tests/getchaintips.py b/qa/rpc-tests/getchaintips.py
index 6a2bcb296..7bbb921ca 100755
--- a/qa/rpc-tests/getchaintips.py
+++ b/qa/rpc-tests/getchaintips.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # on chains of different lengths, and join the network together again.
 # This gives us two tips, verify that it works.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal
 
diff --git a/qa/rpc-tests/hardforkdetection.py b/qa/rpc-tests/hardforkdetection.py
index dbfb5cd34..abab6c19d 100755
--- a/qa/rpc-tests/hardforkdetection.py
+++ b/qa/rpc-tests/hardforkdetection.py
@@ -1,9 +1,11 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 
 #
 # Test hard fork detection
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import assert_equal, start_node
diff --git a/qa/rpc-tests/httpbasics.py b/qa/rpc-tests/httpbasics.py
index b1a4623bd..ca5924c90 100755
--- a/qa/rpc-tests/httpbasics.py
+++ b/qa/rpc-tests/httpbasics.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # Test rpc http basics
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, start_nodes
 
diff --git a/qa/rpc-tests/invalidateblock.py b/qa/rpc-tests/invalidateblock.py
index 5cbd1ea98..ab0ba4a69 100755
--- a/qa/rpc-tests/invalidateblock.py
+++ b/qa/rpc-tests/invalidateblock.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # Test InvalidateBlock code
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import initialize_chain_clean, start_node, \
     connect_nodes_bi, sync_blocks
diff --git a/qa/rpc-tests/invalidblockrequest.py b/qa/rpc-tests/invalidblockrequest.py
index 05b33d772..6e8895f1d 100755
--- a/qa/rpc-tests/invalidblockrequest.py
+++ b/qa/rpc-tests/invalidblockrequest.py
@@ -1,9 +1,11 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 #
 # Distributed under the MIT/X11 software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import ComparisonTestFramework
 from test_framework.util import assert_equal
 from test_framework.comptool import TestManager, TestInstance
diff --git a/qa/rpc-tests/key_import_export.py b/qa/rpc-tests/key_import_export.py
index 87b2daa2b..02638e6a8 100755
--- a/qa/rpc-tests/key_import_export.py
+++ b/qa/rpc-tests/key_import_export.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2017 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from decimal import Decimal
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, assert_greater_than, start_nodes, initialize_chain_clean, connect_nodes_bi
diff --git a/qa/rpc-tests/keypool.py b/qa/rpc-tests/keypool.py
index a7b32e13f..b538742a4 100755
--- a/qa/rpc-tests/keypool.py
+++ b/qa/rpc-tests/keypool.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 
 # Add python-bitcoinrpc to module search path:
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import check_json_precision, initialize_chain, \
     start_nodes, start_node, stop_nodes, wait_bitcoinds, bitcoind_processes
diff --git a/qa/rpc-tests/listtransactions.py b/qa/rpc-tests/listtransactions.py
index a735f41ab..3f508c603 100755
--- a/qa/rpc-tests/listtransactions.py
+++ b/qa/rpc-tests/listtransactions.py
@@ -1,10 +1,12 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 # Exercise the listtransactions API
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 
 from decimal import Decimal
diff --git a/qa/rpc-tests/maxblocksinflight.py b/qa/rpc-tests/maxblocksinflight.py
index beef3d2ea..6ba67940e 100755
--- a/qa/rpc-tests/maxblocksinflight.py
+++ b/qa/rpc-tests/maxblocksinflight.py
@@ -1,9 +1,11 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 #
 # Distributed under the MIT/X11 software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.mininode import NodeConn, NodeConnCB, NetworkThread, \
     EarlyDisconnectError, CInv, msg_inv, mininode_lock
 from test_framework.test_framework import BitcoinTestFramework
diff --git a/qa/rpc-tests/mempool_nu_activation.py b/qa/rpc-tests/mempool_nu_activation.py
index 5f76d17a8..cb54cb7e8 100755
--- a/qa/rpc-tests/mempool_nu_activation.py
+++ b/qa/rpc-tests/mempool_nu_activation.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, initialize_chain_clean, \
     start_node, connect_nodes, wait_and_assert_operationid_status
diff --git a/qa/rpc-tests/mempool_reorg.py b/qa/rpc-tests/mempool_reorg.py
index ad12dadf2..d422b9027 100755
--- a/qa/rpc-tests/mempool_reorg.py
+++ b/qa/rpc-tests/mempool_reorg.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -8,6 +8,8 @@
 # that spend (directly or indirectly) coinbase transactions.
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import assert_equal, assert_raises, start_node, connect_nodes
diff --git a/qa/rpc-tests/mempool_resurrect_test.py b/qa/rpc-tests/mempool_resurrect_test.py
index 1cbbd2cd5..2e31ca198 100755
--- a/qa/rpc-tests/mempool_resurrect_test.py
+++ b/qa/rpc-tests/mempool_resurrect_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -8,6 +8,8 @@
 # the blockchain is re-organized.
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, start_node
 
diff --git a/qa/rpc-tests/mempool_spendcoinbase.py b/qa/rpc-tests/mempool_spendcoinbase.py
index 5366fb955..57716411a 100755
--- a/qa/rpc-tests/mempool_spendcoinbase.py
+++ b/qa/rpc-tests/mempool_spendcoinbase.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -13,6 +13,8 @@
 # but less mature coinbase spends are NOT.
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import assert_equal, assert_greater_than, assert_raises, \
diff --git a/qa/rpc-tests/mempool_tx_expiry.py b/qa/rpc-tests/mempool_tx_expiry.py
index d54260a2b..af84ff3a7 100755
--- a/qa/rpc-tests/mempool_tx_expiry.py
+++ b/qa/rpc-tests/mempool_tx_expiry.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # Test proper expiry for transactions >= version 3
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.authproxy import JSONRPCException
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, \
diff --git a/qa/rpc-tests/mempool_tx_input_limit.py b/qa/rpc-tests/mempool_tx_input_limit.py
index 07282e007..34896a756 100755
--- a/qa/rpc-tests/mempool_tx_input_limit.py
+++ b/qa/rpc-tests/mempool_tx_input_limit.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2017 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import assert_equal, initialize_chain_clean, \
diff --git a/qa/rpc-tests/mergetoaddress_sapling.py b/qa/rpc-tests/mergetoaddress_sapling.py
index 70930cc25..1ab8e61e9 100755
--- a/qa/rpc-tests/mergetoaddress_sapling.py
+++ b/qa/rpc-tests/mergetoaddress_sapling.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from mergetoaddress_helper import MergeToAddressHelper
 
diff --git a/qa/rpc-tests/mergetoaddress_sprout.py b/qa/rpc-tests/mergetoaddress_sprout.py
index 6d7471a9b..88a821ac2 100755
--- a/qa/rpc-tests/mergetoaddress_sprout.py
+++ b/qa/rpc-tests/mergetoaddress_sprout.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from mergetoaddress_helper import MergeToAddressHelper
 
diff --git a/qa/rpc-tests/merkle_blocks.py b/qa/rpc-tests/merkle_blocks.py
index 13b98e140..dda8fbd07 100755
--- a/qa/rpc-tests/merkle_blocks.py
+++ b/qa/rpc-tests/merkle_blocks.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # Test merkleblock fetch/validation
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 import string
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
diff --git a/qa/rpc-tests/nodehandling.py b/qa/rpc-tests/nodehandling.py
index 391a935d0..fd7d8356b 100755
--- a/qa/rpc-tests/nodehandling.py
+++ b/qa/rpc-tests/nodehandling.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # Test node handling
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, connect_nodes_bi, p2p_port
 
diff --git a/qa/rpc-tests/p2p-acceptblock.py b/qa/rpc-tests/p2p-acceptblock.py
index 25221fbed..3f89d786f 100755
--- a/qa/rpc-tests/p2p-acceptblock.py
+++ b/qa/rpc-tests/p2p-acceptblock.py
@@ -1,9 +1,11 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 #
 # Distributed under the MIT/X11 software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.mininode import CBlockHeader, CInv, NodeConn, NodeConnCB, \
     NetworkThread, msg_block, msg_headers, msg_inv, msg_ping, msg_pong, \
     mininode_lock
diff --git a/qa/rpc-tests/p2p_node_bloom.py b/qa/rpc-tests/p2p_node_bloom.py
index 18476a981..9a520c4ed 100755
--- a/qa/rpc-tests/p2p_node_bloom.py
+++ b/qa/rpc-tests/p2p_node_bloom.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.mininode import NodeConn, NodeConnCB, NetworkThread, \
     msg_filteradd, msg_filterclear, mininode_lock, SPROUT_PROTO_VERSION
 from test_framework.test_framework import BitcoinTestFramework
diff --git a/qa/rpc-tests/p2p_nu_peer_management.py b/qa/rpc-tests/p2p_nu_peer_management.py
index 6cedf66bb..aee5bfe18 100755
--- a/qa/rpc-tests/p2p_nu_peer_management.py
+++ b/qa/rpc-tests/p2p_nu_peer_management.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.mininode import (
     NodeConn,
     NodeConnCB,
diff --git a/qa/rpc-tests/p2p_txexpiringsoon.py b/qa/rpc-tests/p2p_txexpiringsoon.py
index 59631624b..cf3bf7de0 100755
--- a/qa/rpc-tests/p2p_txexpiringsoon.py
+++ b/qa/rpc-tests/p2p_txexpiringsoon.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.authproxy import JSONRPCException
 from test_framework.mininode import NodeConn, NodeConnCB, NetworkThread, \
     CTransaction, CInv, msg_mempool, msg_getdata, msg_tx, mininode_lock, \
diff --git a/qa/rpc-tests/p2p_txexpiry_dos.py b/qa/rpc-tests/p2p_txexpiry_dos.py
index ec970435a..98e5f8601 100755
--- a/qa/rpc-tests/p2p_txexpiry_dos.py
+++ b/qa/rpc-tests/p2p_txexpiry_dos.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.mininode import NodeConn, NodeConnCB, NetworkThread, \
     CTransaction, msg_tx, mininode_lock, OVERWINTER_PROTO_VERSION
 from test_framework.test_framework import BitcoinTestFramework
diff --git a/qa/rpc-tests/paymentdisclosure.py b/qa/rpc-tests/paymentdisclosure.py
index 0472325a5..ca73fcb6b 100755
--- a/qa/rpc-tests/paymentdisclosure.py
+++ b/qa/rpc-tests/paymentdisclosure.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2017 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import assert_equal, initialize_chain_clean, \
diff --git a/qa/rpc-tests/prioritisetransaction.py b/qa/rpc-tests/prioritisetransaction.py
index 134b9b160..131644d80 100755
--- a/qa/rpc-tests/prioritisetransaction.py
+++ b/qa/rpc-tests/prioritisetransaction.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2017 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, initialize_chain_clean, \
     start_node, connect_nodes
diff --git a/qa/rpc-tests/proton_test.py b/qa/rpc-tests/proton_test.py
index d9fb27bd3..20c152199 100755
--- a/qa/rpc-tests/proton_test.py
+++ b/qa/rpc-tests/proton_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2017 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -13,6 +13,8 @@
 #     pip install python-qpid-proton
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, bytes_to_hex_str, \
     start_nodes
diff --git a/qa/rpc-tests/proxy_test.py b/qa/rpc-tests/proxy_test.py
index e4fb48820..fec14833c 100755
--- a/qa/rpc-tests/proxy_test.py
+++ b/qa/rpc-tests/proxy_test.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2015 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.socks5 import Socks5Configuration, Socks5Command, Socks5Server, AddressType
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, start_nodes
diff --git a/qa/rpc-tests/pruning.py b/qa/rpc-tests/pruning.py
index 2639060fa..d49cc5812 100755
--- a/qa/rpc-tests/pruning.py
+++ b/qa/rpc-tests/pruning.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -11,6 +11,8 @@
 # This test takes 30 mins or more (up to 2 hours)
 # ********
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import initialize_chain_clean, start_node, \
diff --git a/qa/rpc-tests/rawtransactions.py b/qa/rpc-tests/rawtransactions.py
index 182f87f08..d2dcb857c 100755
--- a/qa/rpc-tests/rawtransactions.py
+++ b/qa/rpc-tests/rawtransactions.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -8,6 +8,8 @@
 # that spend (directly or indirectly) coinbase transactions.
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import assert_equal, initialize_chain_clean, \
diff --git a/qa/rpc-tests/receivedby.py b/qa/rpc-tests/receivedby.py
index 59f7bf258..1a52efce9 100755
--- a/qa/rpc-tests/receivedby.py
+++ b/qa/rpc-tests/receivedby.py
@@ -1,10 +1,12 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 # Exercise the listreceivedbyaddress API
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 
 from decimal import Decimal
diff --git a/qa/rpc-tests/regtest_signrawtransaction.py b/qa/rpc-tests/regtest_signrawtransaction.py
index 93caceb3b..9854cf96f 100755
--- a/qa/rpc-tests/regtest_signrawtransaction.py
+++ b/qa/rpc-tests/regtest_signrawtransaction.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import start_nodes, wait_and_assert_operationid_status
 
diff --git a/qa/rpc-tests/reindex.py b/qa/rpc-tests/reindex.py
index ae7563192..c11314a9f 100755
--- a/qa/rpc-tests/reindex.py
+++ b/qa/rpc-tests/reindex.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # Test -reindex with CheckBlockIndex
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, initialize_chain_clean, \
     start_node, stop_node, wait_bitcoinds
diff --git a/qa/rpc-tests/reorg_limit.py b/qa/rpc-tests/reorg_limit.py
index 12cd146fc..5c46e6d6d 100755
--- a/qa/rpc-tests/reorg_limit.py
+++ b/qa/rpc-tests/reorg_limit.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2017 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # Test reorg limit
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     check_node,
diff --git a/qa/rpc-tests/rest.py b/qa/rpc-tests/rest.py
index b14ec765d..2aa965b53 100755
--- a/qa/rpc-tests/rest.py
+++ b/qa/rpc-tests/rest.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # Test REST interface
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, assert_greater_than, \
     initialize_chain_clean, start_nodes, connect_nodes_bi
diff --git a/qa/rpc-tests/rewind_index.py b/qa/rpc-tests/rewind_index.py
index 8c5c606df..96072098e 100755
--- a/qa/rpc-tests/rewind_index.py
+++ b/qa/rpc-tests/rewind_index.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, initialize_chain_clean, \
     start_nodes, start_node, connect_nodes_bi, bitcoind_processes
diff --git a/qa/rpc-tests/rpcbind_test.py b/qa/rpc-tests/rpcbind_test.py
index 72e14d655..4a6d25463 100755
--- a/qa/rpc-tests/rpcbind_test.py
+++ b/qa/rpc-tests/rpcbind_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 
 # Dependency: python-bitcoinrpc
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.util import assert_equal, check_json_precision, \
     initialize_chain, start_nodes, stop_nodes, wait_bitcoinds, \
     bitcoind_processes, rpc_port
diff --git a/qa/rpc-tests/script_test.py b/qa/rpc-tests/script_test.py
index c3ad541e5..1bbeb2cfc 100755
--- a/qa/rpc-tests/script_test.py
+++ b/qa/rpc-tests/script_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 #
 # Distributed under the MIT/X11 software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -19,6 +19,8 @@ that flag, we use a block time before the switchover date).
 NOTE: This test is very slow and may take more than 40 minutes to run.
 '''
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import ComparisonTestFramework
 from test_framework.comptool import TestInstance, TestManager
 from test_framework.mininode import NetworkThread
diff --git a/qa/rpc-tests/signrawtransaction_offline.py b/qa/rpc-tests/signrawtransaction_offline.py
index 0d7def43b..34e29aa25 100755
--- a/qa/rpc-tests/signrawtransaction_offline.py
+++ b/qa/rpc-tests/signrawtransaction_offline.py
@@ -1,4 +1,6 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
+
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
 
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, assert_true, initialize_chain_clean, start_node
diff --git a/qa/rpc-tests/signrawtransactions.py b/qa/rpc-tests/signrawtransactions.py
index 95d242854..51f2eac3e 100755
--- a/qa/rpc-tests/signrawtransactions.py
+++ b/qa/rpc-tests/signrawtransactions.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2015 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, initialize_chain_clean, \
     start_nodes
diff --git a/qa/rpc-tests/smartfees.py b/qa/rpc-tests/smartfees.py
index e111a406b..168c1699b 100755
--- a/qa/rpc-tests/smartfees.py
+++ b/qa/rpc-tests/smartfees.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014-2015 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # Test fee estimation code
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import start_node, connect_nodes, \
     sync_blocks, sync_mempools
diff --git a/qa/rpc-tests/txn_doublespend.py b/qa/rpc-tests/txn_doublespend.py
index bbe383d16..f342a6f8b 100755
--- a/qa/rpc-tests/txn_doublespend.py
+++ b/qa/rpc-tests/txn_doublespend.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # Test proper accounting with malleable transactions
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, connect_nodes, \
     sync_blocks, gather_inputs
diff --git a/qa/rpc-tests/wallet.py b/qa/rpc-tests/wallet.py
index 40dc54d8f..2b3517740 100755
--- a/qa/rpc-tests/wallet.py
+++ b/qa/rpc-tests/wallet.py
@@ -1,8 +1,9 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
 
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
diff --git a/qa/rpc-tests/wallet_1941.py b/qa/rpc-tests/wallet_1941.py
index 774df07f6..01bfb8cbb 100755
--- a/qa/rpc-tests/wallet_1941.py
+++ b/qa/rpc-tests/wallet_1941.py
@@ -1,10 +1,12 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2016 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 # This is a regression test for #1941.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, initialize_chain_clean, \
     initialize_datadir, start_nodes, start_node, connect_nodes_bi, \
diff --git a/qa/rpc-tests/wallet_addresses.py b/qa/rpc-tests/wallet_addresses.py
index acf50c539..ef0e0bde7 100755
--- a/qa/rpc-tests/wallet_addresses.py
+++ b/qa/rpc-tests/wallet_addresses.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, start_nodes
 
diff --git a/qa/rpc-tests/wallet_anchorfork.py b/qa/rpc-tests/wallet_anchorfork.py
index 21361c4d2..3dfd3c46a 100755
--- a/qa/rpc-tests/wallet_anchorfork.py
+++ b/qa/rpc-tests/wallet_anchorfork.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, initialize_chain_clean, \
     start_nodes, stop_nodes, connect_nodes_bi, \
diff --git a/qa/rpc-tests/wallet_changeindicator.py b/qa/rpc-tests/wallet_changeindicator.py
index b85fa4664..0a8c2bdbd 100755
--- a/qa/rpc-tests/wallet_changeindicator.py
+++ b/qa/rpc-tests/wallet_changeindicator.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, assert_true, assert_false, wait_and_assert_operationid_status
 
diff --git a/qa/rpc-tests/wallet_import_export.py b/qa/rpc-tests/wallet_import_export.py
index cdcc01d1f..57f69aee5 100755
--- a/qa/rpc-tests/wallet_import_export.py
+++ b/qa/rpc-tests/wallet_import_export.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, assert_true, start_nodes
 
diff --git a/qa/rpc-tests/wallet_listnotes.py b/qa/rpc-tests/wallet_listnotes.py
index 04428a3e4..5e5974e5a 100755
--- a/qa/rpc-tests/wallet_listnotes.py
+++ b/qa/rpc-tests/wallet_listnotes.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, start_nodes, wait_and_assert_operationid_status
 
diff --git a/qa/rpc-tests/wallet_listreceived.py b/qa/rpc-tests/wallet_listreceived.py
index f74a6c50e..d5faa3d0a 100755
--- a/qa/rpc-tests/wallet_listreceived.py
+++ b/qa/rpc-tests/wallet_listreceived.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, assert_true, assert_false
 from test_framework.util import start_nodes, wait_and_assert_operationid_status
diff --git a/qa/rpc-tests/wallet_mergetoaddress.py b/qa/rpc-tests/wallet_mergetoaddress.py
index 6b75a31d9..3c2f84aa8 100755
--- a/qa/rpc-tests/wallet_mergetoaddress.py
+++ b/qa/rpc-tests/wallet_mergetoaddress.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2017 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import assert_equal, initialize_chain_clean, \
diff --git a/qa/rpc-tests/wallet_nullifiers.py b/qa/rpc-tests/wallet_nullifiers.py
index 237e85bed..bbf9e64f3 100755
--- a/qa/rpc-tests/wallet_nullifiers.py
+++ b/qa/rpc-tests/wallet_nullifiers.py
@@ -1,8 +1,9 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2016 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
 
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, assert_true, bitcoind_processes, \
diff --git a/qa/rpc-tests/wallet_overwintertx.py b/qa/rpc-tests/wallet_overwintertx.py
index cb59f29fa..7f7488f67 100755
--- a/qa/rpc-tests/wallet_overwintertx.py
+++ b/qa/rpc-tests/wallet_overwintertx.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, initialize_chain_clean, \
     start_nodes, connect_nodes_bi, wait_and_assert_operationid_status
diff --git a/qa/rpc-tests/wallet_persistence.py b/qa/rpc-tests/wallet_persistence.py
index 912e6e879..cdc4af3f7 100755
--- a/qa/rpc-tests/wallet_persistence.py
+++ b/qa/rpc-tests/wallet_persistence.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_equal, assert_true,
diff --git a/qa/rpc-tests/wallet_protectcoinbase.py b/qa/rpc-tests/wallet_protectcoinbase.py
index 288172b32..54fc6c580 100755
--- a/qa/rpc-tests/wallet_protectcoinbase.py
+++ b/qa/rpc-tests/wallet_protectcoinbase.py
@@ -1,8 +1,9 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2016 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
 
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
diff --git a/qa/rpc-tests/wallet_sapling.py b/qa/rpc-tests/wallet_sapling.py
index 82a151361..134e83e53 100755
--- a/qa/rpc-tests/wallet_sapling.py
+++ b/qa/rpc-tests/wallet_sapling.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2018 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import (
diff --git a/qa/rpc-tests/wallet_shieldcoinbase.py b/qa/rpc-tests/wallet_shieldcoinbase.py
index d8366c81d..232d772c5 100755
--- a/qa/rpc-tests/wallet_shieldcoinbase.py
+++ b/qa/rpc-tests/wallet_shieldcoinbase.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2017 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import assert_equal, initialize_chain_clean, \
diff --git a/qa/rpc-tests/wallet_shieldcoinbase_sapling.py b/qa/rpc-tests/wallet_shieldcoinbase_sapling.py
index d5d130329..c220511fc 100755
--- a/qa/rpc-tests/wallet_shieldcoinbase_sapling.py
+++ b/qa/rpc-tests/wallet_shieldcoinbase_sapling.py
@@ -1,4 +1,6 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 import inspect
 import os
 
diff --git a/qa/rpc-tests/wallet_shieldcoinbase_sprout.py b/qa/rpc-tests/wallet_shieldcoinbase_sprout.py
index 619ae7caf..9bced5d99 100755
--- a/qa/rpc-tests/wallet_shieldcoinbase_sprout.py
+++ b/qa/rpc-tests/wallet_shieldcoinbase_sprout.py
@@ -1,4 +1,6 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 import inspect
 import os
 
diff --git a/qa/rpc-tests/wallet_treestate.py b/qa/rpc-tests/wallet_treestate.py
index 802d9368c..eca42eb69 100755
--- a/qa/rpc-tests/wallet_treestate.py
+++ b/qa/rpc-tests/wallet_treestate.py
@@ -1,8 +1,9 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2016 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
 
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, initialize_chain_clean, \
diff --git a/qa/rpc-tests/walletbackup.py b/qa/rpc-tests/walletbackup.py
index 78128ad49..f8bc54cdd 100755
--- a/qa/rpc-tests/walletbackup.py
+++ b/qa/rpc-tests/walletbackup.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -33,6 +33,8 @@ Shutdown again, restore using importwallet,
 and confirm again balances are correct.
 """
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import assert_equal, initialize_chain_clean, \
diff --git a/qa/rpc-tests/zapwallettxes.py b/qa/rpc-tests/zapwallettxes.py
index 5da4ba125..1298ff05c 100755
--- a/qa/rpc-tests/zapwallettxes.py
+++ b/qa/rpc-tests/zapwallettxes.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2014 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import assert_equal, initialize_chain_clean, \
diff --git a/qa/rpc-tests/zcjoinsplit.py b/qa/rpc-tests/zcjoinsplit.py
index 7e5aba6e3..6d9ba860b 100755
--- a/qa/rpc-tests/zcjoinsplit.py
+++ b/qa/rpc-tests/zcjoinsplit.py
@@ -1,9 +1,11 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 
 #
 # Test joinsplit semantics
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, start_node, \
     gather_inputs
diff --git a/qa/rpc-tests/zcjoinsplitdoublespend.py b/qa/rpc-tests/zcjoinsplitdoublespend.py
index 98837b57e..37e7d3a69 100755
--- a/qa/rpc-tests/zcjoinsplitdoublespend.py
+++ b/qa/rpc-tests/zcjoinsplitdoublespend.py
@@ -1,9 +1,11 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 
 #
 # Tests a joinsplit double-spend and a subsequent reorg.
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import assert_equal, connect_nodes, \
diff --git a/qa/rpc-tests/zkey_import_export.py b/qa/rpc-tests/zkey_import_export.py
index cec761b92..4a2208221 100755
--- a/qa/rpc-tests/zkey_import_export.py
+++ b/qa/rpc-tests/zkey_import_export.py
@@ -1,8 +1,10 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2017 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from decimal import Decimal
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, assert_greater_than, start_nodes,\
diff --git a/qa/rpc-tests/zmq_test.py b/qa/rpc-tests/zmq_test.py
index d70e73114..38ed8e9b2 100755
--- a/qa/rpc-tests/zmq_test.py
+++ b/qa/rpc-tests/zmq_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2015 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -7,6 +7,8 @@
 # Test ZMQ interface
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, bytes_to_hex_str, start_nodes
 
diff --git a/qa/zcash/create_wallet_200k_utxos.py b/qa/zcash/create_wallet_200k_utxos.py
index d4a1d9d48..d7f2d10eb 100755
--- a/qa/zcash/create_wallet_200k_utxos.py
+++ b/qa/zcash/create_wallet_200k_utxos.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python
 # Copyright (c) 2017 The Zcash developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
@@ -13,6 +13,8 @@
 # - Archive the resulting /tmp/test###### directory
 #
 
+import sys; assert sys.version_info < (3,), ur"This script does not run under Python 3. Please use Python 2.7.x."
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_equal,