diff --git a/Makefile.am b/Makefile.am
index d6cbd7cb1..0929a59ed 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -110,7 +110,7 @@ osx_volname:
 
 if BUILD_DARWIN
 $(OSX_DMG): $(OSX_APP_BUILT) $(OSX_PACKAGING)
-	$(OSX_DEPLOY_SCRIPT) $(OSX_APP) -add-qt-tr $(OSX_QT_TRANSLATIONS) -translations-dir=$(QT_TRANSLATION_DIR) -dmg -fancy $(OSX_FANCY_PLIST) -verbose 2 -volname $(OSX_VOLNAME)
+	$(PYTHON) $(OSX_DEPLOY_SCRIPT) $(OSX_APP) -add-qt-tr $(OSX_QT_TRANSLATIONS) -translations-dir=$(QT_TRANSLATION_DIR) -dmg -fancy $(OSX_FANCY_PLIST) -verbose 2 -volname $(OSX_VOLNAME)
 
 deploydir: $(OSX_DMG)
 else
@@ -134,10 +134,10 @@ $(APP_DIST_DIR)/.background/$(OSX_BACKGROUND_IMAGE): $(OSX_BACKGROUND_IMAGE_DPIF
 	$(TIFFCP) -c none $(OSX_BACKGROUND_IMAGE_DPIFILES) $@
 
 $(APP_DIST_DIR)/.DS_Store: $(OSX_DSSTORE_GEN)
-	$< "$@" "$(OSX_VOLNAME)"
+	$(PYTHON) $< "$@" "$(OSX_VOLNAME)"
 
 $(APP_DIST_DIR)/$(OSX_APP)/Contents/MacOS/Bitcoin-Qt: $(OSX_APP_BUILT) $(OSX_PACKAGING)
-	INSTALLNAMETOOL=$(INSTALLNAMETOOL)  OTOOL=$(OTOOL) STRIP=$(STRIP) $(OSX_DEPLOY_SCRIPT) $(OSX_APP) -translations-dir=$(QT_TRANSLATION_DIR) -add-qt-tr $(OSX_QT_TRANSLATIONS) -verbose 2
+	INSTALLNAMETOOL=$(INSTALLNAMETOOL)  OTOOL=$(OTOOL) STRIP=$(STRIP) $(PYTHON) $(OSX_DEPLOY_SCRIPT) $(OSX_APP) -translations-dir=$(QT_TRANSLATION_DIR) -add-qt-tr $(OSX_QT_TRANSLATIONS) -verbose 2
 
 deploydir: $(APP_DIST_EXTRAS)
 endif
diff --git a/configure.ac b/configure.ac
index 939dfeaab..8596307f3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -60,7 +60,7 @@ AC_PATH_TOOL(STRIP, strip)
 AC_PATH_TOOL(GCOV, gcov)
 AC_PATH_PROG(LCOV, lcov)
 AC_PATH_PROG(JAVA, java)
-AC_PATH_PROG(PYTHON, python)
+AC_PATH_PROGS([PYTHON], [python3 python2.7 python2 python])
 AC_PATH_PROG(GENHTML, genhtml)
 AC_PATH_PROG([GIT], [git])
 AC_PATH_PROG(CCACHE,ccache)
diff --git a/contrib/devtools/security-check.py b/contrib/devtools/security-check.py
index 0319f739c..301fea85c 100755
--- a/contrib/devtools/security-check.py
+++ b/contrib/devtools/security-check.py
@@ -5,7 +5,7 @@ Exit status will be 0 if successful, and the program will be silent.
 Otherwise the exit status will be 1 and it will log which executables failed which checks.
 Needs `readelf` (for ELF) and `objdump` (for PE).
 '''
-from __future__ import division,print_function
+from __future__ import division,print_function,unicode_literals
 import subprocess
 import sys
 import os
@@ -23,9 +23,9 @@ def check_ELF_PIE(executable):
         raise IOError('Error opening file')
 
     ok = False
-    for line in stdout.split('\n'):
+    for line in stdout.split(b'\n'):
         line = line.split()
-        if len(line)>=2 and line[0] == 'Type:' and line[1] == 'DYN':
+        if len(line)>=2 and line[0] == b'Type:' and line[1] == b'DYN':
             ok = True
     return ok
 
@@ -38,17 +38,17 @@ def get_ELF_program_headers(executable):
     in_headers = False
     count = 0
     headers = []
-    for line in stdout.split('\n'):
-        if line.startswith('Program Headers:'):
+    for line in stdout.split(b'\n'):
+        if line.startswith(b'Program Headers:'):
             in_headers = True
-        if line == '':
+        if line == b'':
             in_headers = False
         if in_headers:
             if count == 1: # header line
-                ofs_typ = line.find('Type')
-                ofs_offset = line.find('Offset')
-                ofs_flags = line.find('Flg')
-                ofs_align = line.find('Align')
+                ofs_typ = line.find(b'Type')
+                ofs_offset = line.find(b'Offset')
+                ofs_flags = line.find(b'Flg')
+                ofs_align = line.find(b'Align')
                 if ofs_typ == -1 or ofs_offset == -1 or ofs_flags == -1 or ofs_align  == -1:
                     raise ValueError('Cannot parse elfread -lW output')
             elif count > 1:
@@ -65,9 +65,9 @@ def check_ELF_NX(executable):
     have_wx = False
     have_gnu_stack = False
     for (typ, flags) in get_ELF_program_headers(executable):
-        if typ == 'GNU_STACK':
+        if typ == b'GNU_STACK':
             have_gnu_stack = True
-        if 'W' in flags and 'E' in flags: # section is both writable and executable
+        if b'W' in flags and b'E' in flags: # section is both writable and executable
             have_wx = True
     return have_gnu_stack and not have_wx
 
@@ -84,7 +84,7 @@ def check_ELF_RELRO(executable):
         # However, the dynamic linker need to write to this area so these are RW.
         # Glibc itself takes care of mprotecting this area R after relocations are finished.
         # See also http://permalink.gmane.org/gmane.comp.gnu.binutils/71347
-        if typ == 'GNU_RELRO':
+        if typ == b'GNU_RELRO':
             have_gnu_relro = True
 
     have_bindnow = False
@@ -92,9 +92,9 @@ def check_ELF_RELRO(executable):
     (stdout, stderr) = p.communicate()
     if p.returncode:
         raise IOError('Error opening file')
-    for line in stdout.split('\n'):
+    for line in stdout.split(b'\n'):
         tokens = line.split()
-        if len(tokens)>1 and tokens[1] == '(BIND_NOW)' or (len(tokens)>2 and tokens[1] == '(FLAGS)' and 'BIND_NOW' in tokens[2]):
+        if len(tokens)>1 and tokens[1] == b'(BIND_NOW)' or (len(tokens)>2 and tokens[1] == b'(FLAGS)' and b'BIND_NOW' in tokens[2]):
             have_bindnow = True
     return have_gnu_relro and have_bindnow
 
@@ -107,8 +107,8 @@ def check_ELF_Canary(executable):
     if p.returncode:
         raise IOError('Error opening file')
     ok = False
-    for line in stdout.split('\n'):
-        if '__stack_chk_fail' in line:
+    for line in stdout.split(b'\n'):
+        if b'__stack_chk_fail' in line:
             ok = True
     return ok
 
diff --git a/contrib/devtools/symbol-check.py b/contrib/devtools/symbol-check.py
index 4ad5136f7..e26c0fbb9 100755
--- a/contrib/devtools/symbol-check.py
+++ b/contrib/devtools/symbol-check.py
@@ -11,7 +11,7 @@ Example usage:
 
     find ../gitian-builder/build -type f -executable | xargs python contrib/devtools/symbol-check.py
 '''
-from __future__ import division, print_function
+from __future__ import division, print_function, unicode_literals
 import subprocess
 import re
 import sys
@@ -47,28 +47,28 @@ MAX_VERSIONS = {
 
 # Ignore symbols that are exported as part of every executable
 IGNORE_EXPORTS = {
-'_edata', '_end', '_init', '__bss_start', '_fini', '_IO_stdin_used'
+b'_edata', b'_end', b'_init', b'__bss_start', b'_fini', b'_IO_stdin_used'
 }
 READELF_CMD = os.getenv('READELF', '/usr/bin/readelf')
 CPPFILT_CMD = os.getenv('CPPFILT', '/usr/bin/c++filt')
 # Allowed NEEDED libraries
 ALLOWED_LIBRARIES = {
 # bitcoind and bitcoin-qt
-'libgcc_s.so.1', # GCC base support
-'libc.so.6', # C library
-'libpthread.so.0', # threading
-'libanl.so.1', # DNS resolve
-'libm.so.6', # math library
-'librt.so.1', # real-time (clock)
-'ld-linux-x86-64.so.2', # 64-bit dynamic linker
-'ld-linux.so.2', # 32-bit dynamic linker
+b'libgcc_s.so.1', # GCC base support
+b'libc.so.6', # C library
+b'libpthread.so.0', # threading
+b'libanl.so.1', # DNS resolve
+b'libm.so.6', # math library
+b'librt.so.1', # real-time (clock)
+b'ld-linux-x86-64.so.2', # 64-bit dynamic linker
+b'ld-linux.so.2', # 32-bit dynamic linker
 # bitcoin-qt only
-'libX11-xcb.so.1', # part of X11
-'libX11.so.6', # part of X11
-'libxcb.so.1', # part of X11
-'libfontconfig.so.1', # font support
-'libfreetype.so.6', # font parsing
-'libdl.so.2' # programming interface to dynamic linker
+b'libX11-xcb.so.1', # part of X11
+b'libX11.so.6', # part of X11
+b'libxcb.so.1', # part of X11
+b'libfontconfig.so.1', # font support
+b'libfreetype.so.6', # font parsing
+b'libdl.so.2' # programming interface to dynamic linker
 }
 
 class CPPFilt(object):
@@ -81,7 +81,8 @@ class CPPFilt(object):
         self.proc = subprocess.Popen(CPPFILT_CMD, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
 
     def __call__(self, mangled):
-        self.proc.stdin.write(mangled + '\n')
+        self.proc.stdin.write(mangled + b'\n')
+        self.proc.stdin.flush()
         return self.proc.stdout.readline().rstrip()
 
     def close(self):
@@ -99,24 +100,24 @@ def read_symbols(executable, imports=True):
     if p.returncode:
         raise IOError('Could not read symbols for %s: %s' % (executable, stderr.strip()))
     syms = []
-    for line in stdout.split('\n'):
+    for line in stdout.split(b'\n'):
         line = line.split()
-        if len(line)>7 and re.match('[0-9]+:$', line[0]):
-            (sym, _, version) = line[7].partition('@')
-            is_import = line[6] == 'UND'
-            if version.startswith('@'):
+        if len(line)>7 and re.match(b'[0-9]+:$', line[0]):
+            (sym, _, version) = line[7].partition(b'@')
+            is_import = line[6] == b'UND'
+            if version.startswith(b'@'):
                 version = version[1:]
             if is_import == imports:
                 syms.append((sym, version))
     return syms
 
 def check_version(max_versions, version):
-    if '_' in version:
-        (lib, _, ver) = version.rpartition('_')
+    if b'_' in version:
+        (lib, _, ver) = version.rpartition(b'_')
     else:
         lib = version
         ver = '0'
-    ver = tuple([int(x) for x in ver.split('.')])
+    ver = tuple([int(x) for x in ver.split(b'.')])
     if not lib in max_versions:
         return False
     return ver <= max_versions[lib]
@@ -127,10 +128,10 @@ def read_libraries(filename):
     if p.returncode:
         raise IOError('Error opening file')
     libraries = []
-    for line in stdout.split('\n'):
+    for line in stdout.split(b'\n'):
         tokens = line.split()
-        if len(tokens)>2 and tokens[1] == '(NEEDED)':
-            match = re.match('^Shared library: \[(.*)\]$', ' '.join(tokens[2:]))
+        if len(tokens)>2 and tokens[1] == b'(NEEDED)':
+            match = re.match(b'^Shared library: \[(.*)\]$', b' '.join(tokens[2:]))
             if match:
                 libraries.append(match.group(1))
             else:
@@ -144,18 +145,18 @@ if __name__ == '__main__':
         # Check imported symbols
         for sym,version in read_symbols(filename, True):
             if version and not check_version(MAX_VERSIONS, version):
-                print('%s: symbol %s from unsupported version %s' % (filename, cppfilt(sym), version))
+                print('%s: symbol %s from unsupported version %s' % (filename, cppfilt(sym).decode('utf-8'), version.decode('utf-8')))
                 retval = 1
         # Check exported symbols
         for sym,version in read_symbols(filename, False):
             if sym in IGNORE_EXPORTS:
                 continue
-            print('%s: export of symbol %s not allowed' % (filename, cppfilt(sym)))
+            print('%s: export of symbol %s not allowed' % (filename, cppfilt(sym).decode('utf-8')))
             retval = 1
         # Check dependency libraries
         for library_name in read_libraries(filename):
             if library_name not in ALLOWED_LIBRARIES:
-                print('%s: NEEDED library %s is not allowed' % (filename, library_name))
+                print('%s: NEEDED library %s is not allowed' % (filename, library_name.decode('utf-8')))
                 retval = 1
 
     exit(retval)
diff --git a/contrib/macdeploy/custom_dsstore.py b/contrib/macdeploy/custom_dsstore.py
index 8481e903a..03e2325fc 100755
--- a/contrib/macdeploy/custom_dsstore.py
+++ b/contrib/macdeploy/custom_dsstore.py
@@ -2,7 +2,7 @@
 # Copyright (c) 2013-2015 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
+from __future__ import division,print_function,unicode_literals
 import biplist
 from ds_store import DSStore
 from mac_alias import Alias
@@ -14,7 +14,7 @@ package_name_ns = sys.argv[2]
 ds = DSStore.open(output_file, 'w+')
 ds['.']['bwsp'] = {
     'ShowStatusBar': False,
-    'WindowBounds': '{{300, 280}, {500, 343}}',
+    'WindowBounds': b'{{300, 280}, {500, 343}}',
     'ContainerShowSidebar': False,
     'SidebarWidth': 0,
     'ShowTabView': False,
@@ -28,7 +28,7 @@ icvp = {
     'gridOffsetX': 0.0,
     'textSize': 12.0,
     'viewOptionsVersion': 1,
-    'backgroundImageAlias': '\x00\x00\x00\x00\x02\x1e\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xd1\x94\\\xb0H+\x00\x05\x00\x00\x00\x98\x0fbackground.tiff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x99\xd19\xb0\xf8\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\x00\x00\r\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0b.background\x00\x00\x10\x00\x08\x00\x00\xd1\x94\\\xb0\x00\x00\x00\x11\x00\x08\x00\x00\xd19\xb0\xf8\x00\x00\x00\x01\x00\x04\x00\x00\x00\x98\x00\x0e\x00 \x00\x0f\x00b\x00a\x00c\x00k\x00g\x00r\x00o\x00u\x00n\x00d\x00.\x00t\x00i\x00f\x00f\x00\x0f\x00\x02\x00\x00\x00\x12\x00\x1c/.background/background.tiff\x00\x14\x01\x06\x00\x00\x00\x00\x01\x06\x00\x02\x00\x00\x0cMacintosh HD\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xce\x97\xab\xc3H+\x00\x00\x01\x88[\x88\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02u\xab\x8d\xd1\x94\\\xb0devrddsk\xff\xff\xff\xff\x00\x00\t \x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x07bitcoin\x00\x00\x10\x00\x08\x00\x00\xce\x97\xab\xc3\x00\x00\x00\x11\x00\x08\x00\x00\xd1\x94\\\xb0\x00\x00\x00\x01\x00\x14\x01\x88[\x88\x00\x16\xa9\t\x00\x08\xfaR\x00\x08\xfaQ\x00\x02d\x8e\x00\x0e\x00\x02\x00\x00\x00\x0f\x00\x1a\x00\x0c\x00M\x00a\x00c\x00i\x00n\x00t\x00o\x00s\x00h\x00 \x00H\x00D\x00\x13\x00\x01/\x00\x00\x15\x00\x02\x00\x14\xff\xff\x00\x00\xff\xff\x00\x00',
+    'backgroundImageAlias': b'\x00\x00\x00\x00\x02\x1e\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xd1\x94\\\xb0H+\x00\x05\x00\x00\x00\x98\x0fbackground.tiff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x99\xd19\xb0\xf8\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\x00\x00\r\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0b.background\x00\x00\x10\x00\x08\x00\x00\xd1\x94\\\xb0\x00\x00\x00\x11\x00\x08\x00\x00\xd19\xb0\xf8\x00\x00\x00\x01\x00\x04\x00\x00\x00\x98\x00\x0e\x00 \x00\x0f\x00b\x00a\x00c\x00k\x00g\x00r\x00o\x00u\x00n\x00d\x00.\x00t\x00i\x00f\x00f\x00\x0f\x00\x02\x00\x00\x00\x12\x00\x1c/.background/background.tiff\x00\x14\x01\x06\x00\x00\x00\x00\x01\x06\x00\x02\x00\x00\x0cMacintosh HD\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xce\x97\xab\xc3H+\x00\x00\x01\x88[\x88\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02u\xab\x8d\xd1\x94\\\xb0devrddsk\xff\xff\xff\xff\x00\x00\t \x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x07bitcoin\x00\x00\x10\x00\x08\x00\x00\xce\x97\xab\xc3\x00\x00\x00\x11\x00\x08\x00\x00\xd1\x94\\\xb0\x00\x00\x00\x01\x00\x14\x01\x88[\x88\x00\x16\xa9\t\x00\x08\xfaR\x00\x08\xfaQ\x00\x02d\x8e\x00\x0e\x00\x02\x00\x00\x00\x0f\x00\x1a\x00\x0c\x00M\x00a\x00c\x00i\x00n\x00t\x00o\x00s\x00h\x00 \x00H\x00D\x00\x13\x00\x01/\x00\x00\x15\x00\x02\x00\x14\xff\xff\x00\x00\xff\xff\x00\x00',
     'backgroundColorBlue': 1.0,
     'iconSize': 96.0,
     'backgroundColorGreen': 1.0,
diff --git a/contrib/macdeploy/macdeployqtplus b/contrib/macdeploy/macdeployqtplus
index 7e6270c74..685ed8e5b 100755
--- a/contrib/macdeploy/macdeployqtplus
+++ b/contrib/macdeploy/macdeployqtplus
@@ -1,5 +1,5 @@
 #!/usr/bin/env python
-
+from __future__ import division, print_function, unicode_literals
 #
 # Copyright (C) 2011  Patrick "p2k" Schneider <me@p2k-network.org>
 #
@@ -201,7 +201,7 @@ class DeploymentInfo(object):
 
 def getFrameworks(binaryPath, verbose):
     if verbose >= 3:
-        print "Inspecting with otool: " + binaryPath
+        print("Inspecting with otool: " + binaryPath)
     otoolbin=os.getenv("OTOOL", "otool")
     otool = subprocess.Popen([otoolbin, "-L", binaryPath], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
     o_stdout, o_stderr = otool.communicate()
@@ -222,8 +222,8 @@ def getFrameworks(binaryPath, verbose):
         info = FrameworkInfo.fromOtoolLibraryLine(line.strip())
         if info is not None:
             if verbose >= 3:
-                print "Found framework:"
-                print info
+                print("Found framework:")
+                print(info)
             libraries.append(info)
     
     return libraries
@@ -234,24 +234,24 @@ def runInstallNameTool(action, *args):
 
 def changeInstallName(oldName, newName, binaryPath, verbose):
     if verbose >= 3:
-        print "Using install_name_tool:"
-        print " in", binaryPath
-        print " change reference", oldName
-        print " to", newName
+        print("Using install_name_tool:")
+        print(" in", binaryPath)
+        print(" change reference", oldName)
+        print(" to", newName)
     runInstallNameTool("change", oldName, newName, binaryPath)
 
 def changeIdentification(id, binaryPath, verbose):
     if verbose >= 3:
-        print "Using install_name_tool:"
-        print " change identification in", binaryPath
-        print " to", id
+        print("Using install_name_tool:")
+        print(" change identification in", binaryPath)
+        print(" to", id)
     runInstallNameTool("id", id, binaryPath)
 
 def runStrip(binaryPath, verbose):
     stripbin=os.getenv("STRIP", "strip")
     if verbose >= 3:
-        print "Using strip:"
-        print " stripped", binaryPath
+        print("Using strip:")
+        print(" stripped", binaryPath)
     subprocess.check_call([stripbin, "-x", binaryPath])
 
 def copyFramework(framework, path, verbose):
@@ -274,8 +274,8 @@ def copyFramework(framework, path, verbose):
     
     shutil.copy2(fromPath, toPath)
     if verbose >= 3:
-        print "Copied:", fromPath
-        print " to:", toPath
+        print("Copied:", fromPath)
+        print(" to:", toPath)
 
     permissions = os.stat(toPath)
     if not permissions.st_mode & stat.S_IWRITE:
@@ -288,14 +288,14 @@ def copyFramework(framework, path, verbose):
         if not os.path.exists(linkfrom):
             os.symlink(linkto, linkfrom)
             if verbose >= 2:
-                print "Linked:", linkfrom, "->", linkto
+                print("Linked:", linkfrom, "->", linkto)
         fromResourcesDir = framework.sourceResourcesDirectory
         if os.path.exists(fromResourcesDir):
             toResourcesDir = os.path.join(path, framework.destinationResourcesDirectory)
             shutil.copytree(fromResourcesDir, toResourcesDir, symlinks=True)
             if verbose >= 3:
-                print "Copied resources:", fromResourcesDir
-                print " to:", toResourcesDir
+                print("Copied resources:", fromResourcesDir)
+                print(" to:", toResourcesDir)
         fromContentsDir = framework.sourceVersionContentsDirectory
         if not os.path.exists(fromContentsDir):
             fromContentsDir = framework.sourceContentsDirectory
@@ -304,16 +304,16 @@ def copyFramework(framework, path, verbose):
             shutil.copytree(fromContentsDir, toContentsDir, symlinks=True)
             contentslinkfrom = os.path.join(path, framework.destinationContentsDirectory)
             if verbose >= 3:
-                print "Copied Contents:", fromContentsDir
-                print " to:", toContentsDir
+                print("Copied Contents:", fromContentsDir)
+                print(" to:", toContentsDir)
     elif framework.frameworkName.startswith("libQtGui"): # Copy qt_menu.nib (applies to non-framework layout)
         qtMenuNibSourcePath = os.path.join(framework.frameworkDirectory, "Resources", "qt_menu.nib")
         qtMenuNibDestinationPath = os.path.join(path, "Contents", "Resources", "qt_menu.nib")
         if os.path.exists(qtMenuNibSourcePath) and not os.path.exists(qtMenuNibDestinationPath):
             shutil.copytree(qtMenuNibSourcePath, qtMenuNibDestinationPath, symlinks=True)
             if verbose >= 3:
-                print "Copied for libQtGui:", qtMenuNibSourcePath
-                print " to:", qtMenuNibDestinationPath
+                print("Copied for libQtGui:", qtMenuNibSourcePath)
+                print(" to:", qtMenuNibDestinationPath)
     
     return toPath
 
@@ -326,7 +326,7 @@ def deployFrameworks(frameworks, bundlePath, binaryPath, strip, verbose, deploym
         deploymentInfo.deployedFrameworks.append(framework.frameworkName)
         
         if verbose >= 2:
-            print "Processing", framework.frameworkName, "..."
+            print("Processing", framework.frameworkName, "...")
         
         # Get the Qt path from one of the Qt frameworks
         if deploymentInfo.qtPath is None and framework.isQtFramework():
@@ -334,7 +334,7 @@ def deployFrameworks(frameworks, bundlePath, binaryPath, strip, verbose, deploym
         
         if framework.installName.startswith("@executable_path") or framework.installName.startswith(bundlePath):
             if verbose >= 2:
-                print framework.frameworkName, "already deployed, skipping."
+                print(framework.frameworkName, "already deployed, skipping.")
             continue
         
         # install_name_tool the new id into the binary
@@ -366,7 +366,7 @@ def deployFrameworks(frameworks, bundlePath, binaryPath, strip, verbose, deploym
 def deployFrameworksForAppBundle(applicationBundle, strip, verbose):
     frameworks = getFrameworks(applicationBundle.binaryPath, verbose)
     if len(frameworks) == 0 and verbose >= 1:
-        print "Warning: Could not find any external frameworks to deploy in %s." % (applicationBundle.path)
+        print("Warning: Could not find any external frameworks to deploy in %s." % (applicationBundle.path))
         return DeploymentInfo()
     else:
         return deployFrameworks(frameworks, applicationBundle.path, applicationBundle.binaryPath, strip, verbose)
@@ -444,7 +444,7 @@ def deployPlugins(appBundleInfo, deploymentInfo, strip, verbose):
     
     for pluginDirectory, pluginName in plugins:
         if verbose >= 2:
-            print "Processing plugin", os.path.join(pluginDirectory, pluginName), "..."
+            print("Processing plugin", os.path.join(pluginDirectory, pluginName), "...")
         
         sourcePath = os.path.join(deploymentInfo.pluginPath, pluginDirectory, pluginName)
         destinationDirectory = os.path.join(appBundleInfo.pluginPath, pluginDirectory)
@@ -454,8 +454,8 @@ def deployPlugins(appBundleInfo, deploymentInfo, strip, verbose):
         destinationPath = os.path.join(destinationDirectory, pluginName)
         shutil.copy2(sourcePath, destinationPath)
         if verbose >= 3:
-            print "Copied:", sourcePath
-            print " to:", destinationPath
+            print("Copied:", sourcePath)
+            print(" to:", destinationPath)
         
         if strip:
             runStrip(destinationPath, verbose)
@@ -525,7 +525,7 @@ if config.translations_dir and config.translations_dir[0]:
 
 for p in config.add_resources:
     if verbose >= 3:
-        print "Checking for \"%s\"..." % p
+        print("Checking for \"%s\"..." % p)
     if not os.path.exists(p):
         if verbose >= 1:
             sys.stderr.write("Error: Could not find additional resource file \"%s\"\n" % (p))
@@ -535,7 +535,7 @@ for p in config.add_resources:
 
 if len(config.fancy) == 1:
     if verbose >= 3:
-        print "Fancy: Importing plistlib..."
+        print("Fancy: Importing plistlib...")
     try:
         import plistlib
     except ImportError:
@@ -545,7 +545,7 @@ if len(config.fancy) == 1:
     
     p = config.fancy[0]
     if verbose >= 3:
-        print "Fancy: Loading \"%s\"..." % p
+        print("Fancy: Loading \"%s\"..." % p)
     if not os.path.exists(p):
         if verbose >= 1:
             sys.stderr.write("Error: Could not find fancy disk image plist at \"%s\"\n" % (p))
@@ -559,23 +559,23 @@ if len(config.fancy) == 1:
         sys.exit(1)
     
     try:
-        assert not fancy.has_key("window_bounds") or (isinstance(fancy["window_bounds"], list) and len(fancy["window_bounds"]) == 4)
-        assert not fancy.has_key("background_picture") or isinstance(fancy["background_picture"], str)
-        assert not fancy.has_key("icon_size") or isinstance(fancy["icon_size"], int)
-        assert not fancy.has_key("applications_symlink") or isinstance(fancy["applications_symlink"], bool)
-        if fancy.has_key("items_position"):
+        assert "window_bounds" not in fancy or (isinstance(fancy["window_bounds"], list) and len(fancy["window_bounds"]) == 4)
+        assert "background_picture" not in fancy or isinstance(fancy["background_picture"], str)
+        assert "icon_size" not in fancy or isinstance(fancy["icon_size"], int)
+        assert "applications_symlink" not in fancy or isinstance(fancy["applications_symlink"], bool)
+        if "items_position" in fancy:
             assert isinstance(fancy["items_position"], dict)
-            for key, value in fancy["items_position"].iteritems():
+            for key, value in fancy["items_position"].items():
                 assert isinstance(value, list) and len(value) == 2 and isinstance(value[0], int) and isinstance(value[1], int)
     except:
         if verbose >= 1:
             sys.stderr.write("Error: Bad format of fancy disk image plist at \"%s\"\n" % (p))
         sys.exit(1)
     
-    if fancy.has_key("background_picture"):
+    if "background_picture" in fancy:
         bp = fancy["background_picture"]
         if verbose >= 3:
-            print "Fancy: Resolving background picture \"%s\"..." % bp
+            print("Fancy: Resolving background picture \"%s\"..." % bp)
         if not os.path.exists(bp):
             bp = os.path.join(os.path.dirname(p), bp)
             if not os.path.exists(bp):
@@ -591,7 +591,7 @@ else:
 
 if os.path.exists("dist"):
     if verbose >= 2:
-        print "+ Removing old dist folder +"
+        print("+ Removing old dist folder +")
     
     shutil.rmtree("dist")
 
@@ -607,9 +607,9 @@ else:
 target = os.path.join("dist", "Bitcoin-Qt.app")
 
 if verbose >= 2:
-    print "+ Copying source bundle +"
+    print("+ Copying source bundle +")
 if verbose >= 3:
-    print app_bundle, "->", target
+    print(app_bundle, "->", target)
 
 os.mkdir("dist")
 shutil.copytree(app_bundle, target, symlinks=True)
@@ -619,7 +619,7 @@ applicationBundle = ApplicationBundleInfo(target)
 # ------------------------------------------------
 
 if verbose >= 2:
-    print "+ Deploying frameworks +"
+    print("+ Deploying frameworks +")
 
 try:
     deploymentInfo = deployFrameworksForAppBundle(applicationBundle, config.strip, verbose)
@@ -638,7 +638,7 @@ except RuntimeError as e:
 
 if config.plugins:
     if verbose >= 2:
-        print "+ Deploying plugins +"
+        print("+ Deploying plugins +")
     
     try:
         deployPlugins(applicationBundle, deploymentInfo, config.strip, verbose)
@@ -664,7 +664,7 @@ else:
     for lng_file in add_qt_tr:
         p = os.path.join(qt_tr_dir, lng_file)
         if verbose >= 3:
-            print "Checking for \"%s\"..." % p
+            print("Checking for \"%s\"..." % p)
         if not os.path.exists(p):
             if verbose >= 1:
                 sys.stderr.write("Error: Could not find Qt translation file \"%s\"\n" % (lng_file))
@@ -673,7 +673,7 @@ else:
 # ------------------------------------------------
 
 if verbose >= 2:
-    print "+ Installing qt.conf +"
+    print("+ Installing qt.conf +")
 
 f = open(os.path.join(applicationBundle.resourcesPath, "qt.conf"), "wb")
 f.write(qt_conf)
@@ -682,22 +682,22 @@ f.close()
 # ------------------------------------------------
 
 if len(add_qt_tr) > 0 and verbose >= 2:
-    print "+ Adding Qt translations +"
+    print("+ Adding Qt translations +")
 
 for lng_file in add_qt_tr:
     if verbose >= 3:
-        print os.path.join(qt_tr_dir, lng_file), "->", os.path.join(applicationBundle.resourcesPath, lng_file)
+        print(os.path.join(qt_tr_dir, lng_file), "->", os.path.join(applicationBundle.resourcesPath, lng_file))
     shutil.copy2(os.path.join(qt_tr_dir, lng_file), os.path.join(applicationBundle.resourcesPath, lng_file))
 
 # ------------------------------------------------
 
 if len(config.add_resources) > 0 and verbose >= 2:
-    print "+ Adding additional resources +"
+    print("+ Adding additional resources +")
 
 for p in config.add_resources:
     t = os.path.join(applicationBundle.resourcesPath, os.path.basename(p))
     if verbose >= 3:
-        print p, "->", t
+        print(p, "->", t)
     if os.path.isdir(p):
         shutil.copytree(p, t, symlinks=True)
     else:
@@ -706,10 +706,10 @@ for p in config.add_resources:
 # ------------------------------------------------
 
 if config.sign and 'CODESIGNARGS' not in os.environ:
-    print "You must set the CODESIGNARGS environment variable. Skipping signing."
+    print("You must set the CODESIGNARGS environment variable. Skipping signing.")
 elif config.sign:
     if verbose >= 1:
-        print "Code-signing app bundle %s"%(target,)
+        print("Code-signing app bundle %s"%(target,))
     subprocess.check_call("codesign --force %s %s"%(os.environ['CODESIGNARGS'], target), shell=True)
 
 # ------------------------------------------------
@@ -734,7 +734,7 @@ if config.dmg is not None:
 
     def runHDIUtil(verb, image_basename, **kwargs):
         hdiutil_args = ["hdiutil", verb, image_basename + ".dmg"]
-        if kwargs.has_key("capture_stdout"):
+        if "capture_stdout" in kwargs:
             del kwargs["capture_stdout"]
             run = subprocess.check_output
         else:
@@ -744,7 +744,7 @@ if config.dmg is not None:
                 hdiutil_args.append("-verbose")
             run = subprocess.check_call
         
-        for key, value in kwargs.iteritems():
+        for key, value in kwargs.items():
             hdiutil_args.append("-" + key)
             if not value is True:
                 hdiutil_args.append(str(value))
@@ -753,9 +753,9 @@ if config.dmg is not None:
     
     if verbose >= 2:
         if fancy is None:
-            print "+ Creating .dmg disk image +"
+            print("+ Creating .dmg disk image +")
         else:
-            print "+ Preparing .dmg disk image +"
+            print("+ Preparing .dmg disk image +")
     
     if config.dmg != "":
         dmg_name = config.dmg
@@ -770,7 +770,7 @@ if config.dmg is not None:
             sys.exit(e.returncode)
     else:
         if verbose >= 3:
-            print "Determining size of \"dist\"..."
+            print("Determining size of \"dist\"...")
         size = 0
         for path, dirs, files in os.walk("dist"):
             for file in files:
@@ -778,14 +778,14 @@ if config.dmg is not None:
         size += int(size * 0.15)
         
         if verbose >= 3:
-            print "Creating temp image for modification..."
+            print("Creating temp image for modification...")
         try:
             runHDIUtil("create", dmg_name + ".temp", srcfolder="dist", format="UDRW", size=size, volname=volname, ov=True)
         except subprocess.CalledProcessError as e:
             sys.exit(e.returncode)
         
         if verbose >= 3:
-            print "Attaching temp image..."
+            print("Attaching temp image...")
         try:
             output = runHDIUtil("attach", dmg_name + ".temp", readwrite=True, noverify=True, noautoopen=True, capture_stdout=True)
         except subprocess.CalledProcessError as e:
@@ -796,13 +796,13 @@ if config.dmg is not None:
         disk_name = m.group(1)
         
         if verbose >= 2:
-            print "+ Applying fancy settings +"
+            print("+ Applying fancy settings +")
         
-        if fancy.has_key("background_picture"):
+        if "background_picture" in fancy:
             bg_path = os.path.join(disk_root, ".background", os.path.basename(fancy["background_picture"]))
             os.mkdir(os.path.dirname(bg_path))
             if verbose >= 3:
-                print fancy["background_picture"], "->", bg_path
+                print(fancy["background_picture"], "->", bg_path)
             shutil.copy2(fancy["background_picture"], bg_path)
         else:
             bg_path = None
@@ -839,8 +839,8 @@ if config.dmg is not None:
 
         itemscript = Template('set position of item "${item}" of container window to {${position}}')
         items_positions = []
-        if fancy.has_key("items_position"):
-            for name, position in fancy["items_position"].iteritems():
+        if "items_position" in fancy:
+            for name, position in fancy["items_position"].items():
                 params = { "item" : name, "position" : ",".join([str(p) for p in position]) }
                 items_positions.append(itemscript.substitute(params))
 
@@ -851,9 +851,9 @@ if config.dmg is not None:
             "background_commands" : "",
             "items_positions" : "\n                   ".join(items_positions)
             }
-        if fancy.has_key("window_bounds"):
+        if "window_bounds" in fancy:
             params["window.bounds"] = ",".join([str(p) for p in fancy["window_bounds"]])
-        if fancy.has_key("icon_size"):
+        if "icon_size" in fancy:
             params["icon_size"] = str(fancy["icon_size"])
         if bg_path is not None:
             # Set background file, then call SetFile to make it invisible.
@@ -873,7 +873,7 @@ if config.dmg is not None:
             print("Error running osascript.")
 
         if verbose >= 2:
-            print "+ Finalizing .dmg disk image +"
+            print("+ Finalizing .dmg disk image +")
             time.sleep(5)
         
         try:
@@ -886,6 +886,6 @@ if config.dmg is not None:
 # ------------------------------------------------
 
 if verbose >= 2:
-    print "+ Done +"
+    print("+ Done +")
 
 sys.exit(0)
diff --git a/share/qt/extract_strings_qt.py b/share/qt/extract_strings_qt.py
index 2a6e4b930..7728a4377 100755
--- a/share/qt/extract_strings_qt.py
+++ b/share/qt/extract_strings_qt.py
@@ -1,8 +1,9 @@
 #!/usr/bin/python
 '''
-Extract _("...") strings for translation and convert to Qt4 stringdefs so that
+Extract _("...") strings for translation and convert to Qt stringdefs so that
 they can be picked up by Qt linguist.
 '''
+from __future__ import division,print_function,unicode_literals
 from subprocess import Popen, PIPE
 import glob
 import operator
@@ -52,10 +53,14 @@ files = sys.argv[1:]
 
 # xgettext -n --keyword=_ $FILES
 XGETTEXT=os.getenv('XGETTEXT', 'xgettext')
+if not XGETTEXT:
+    print('Cannot extract strings: xgettext utility is not installed or not configured.',file=sys.stderr)
+    print('Please install package "gettext" and re-run \'./configure\'.',file=sys.stderr)
+    exit(1)
 child = Popen([XGETTEXT,'--output=-','-n','--keyword=_'] + files, stdout=PIPE)
 (out, err) = child.communicate()
 
-messages = parse_po(out) 
+messages = parse_po(out.decode('utf-8'))
 
 f = open(OUT_CPP, 'w')
 f.write("""
diff --git a/src/Makefile.qt.include b/src/Makefile.qt.include
index ca4e1e70d..357e4c47f 100644
--- a/src/Makefile.qt.include
+++ b/src/Makefile.qt.include
@@ -391,7 +391,7 @@ SECONDARY: $(QT_QM)
 
 qt/bitcoinstrings.cpp: $(libbitcoin_server_a_SOURCES) $(libbitcoin_wallet_a_SOURCES)
 	@test -n $(XGETTEXT) || echo "xgettext is required for updating translations"
-	$(AM_V_GEN) cd $(srcdir); XGETTEXT=$(XGETTEXT) PACKAGE_NAME="$(PACKAGE_NAME)" COPYRIGHT_HOLDERS="$(COPYRIGHT_HOLDERS)" COPYRIGHT_HOLDERS_SUBSTITUTION="$(COPYRIGHT_HOLDERS_SUBSTITUTION)" ../share/qt/extract_strings_qt.py $^
+	$(AM_V_GEN) cd $(srcdir); XGETTEXT=$(XGETTEXT) PACKAGE_NAME="$(PACKAGE_NAME)" COPYRIGHT_HOLDERS="$(COPYRIGHT_HOLDERS)" COPYRIGHT_HOLDERS_SUBSTITUTION="$(COPYRIGHT_HOLDERS_SUBSTITUTION)" $(PYTHON) ../share/qt/extract_strings_qt.py $^
 
 translate: qt/bitcoinstrings.cpp $(QT_FORMS_UI) $(QT_FORMS_UI) $(BITCOIN_QT_CPP) $(BITCOIN_QT_H) $(BITCOIN_MM)
 	@test -n $(LUPDATE) || echo "lupdate is required for updating translations"
diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index 57f9ac50e..86b27ae68 100644
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -129,7 +129,7 @@ bitcoin_test_clean : FORCE
 
 check-local:
 	@echo "Running test/bitcoin-util-test.py..."
-	$(AM_V_at)srcdir=$(srcdir) PYTHONPATH=$(builddir)/test $(srcdir)/test/bitcoin-util-test.py
+	$(AM_V_at)srcdir=$(srcdir) PYTHONPATH=$(builddir)/test $(PYTHON) $(srcdir)/test/bitcoin-util-test.py
 	$(AM_V_at)$(MAKE) $(AM_MAKEFLAGS) -C secp256k1 check
 if EMBEDDED_UNIVALUE
 	$(AM_V_at)$(MAKE) $(AM_MAKEFLAGS) -C univalue check
diff --git a/src/test/bctest.py b/src/test/bctest.py
index 3a8d0ea51..8105b87ff 100644
--- a/src/test/bctest.py
+++ b/src/test/bctest.py
@@ -1,7 +1,7 @@
 # Copyright 2014 BitPay, Inc.
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
+from __future__ import division,print_function,unicode_literals
 import subprocess
 import os
 import json
diff --git a/src/test/bitcoin-util-test.py b/src/test/bitcoin-util-test.py
index 20afb16a9..95dd3e81b 100755
--- a/src/test/bitcoin-util-test.py
+++ b/src/test/bitcoin-util-test.py
@@ -2,7 +2,7 @@
 # Copyright 2014 BitPay, Inc.
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
+from __future__ import division,print_function,unicode_literals
 import os
 import bctest
 import buildenv