diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 6178a1c7a..d65e107e3 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -210,7 +210,7 @@ UniValue waitfornewblock(const JSONRPCRequest& request)
             + HelpExampleRpc("waitfornewblock", "1000")
         );
     int timeout = 0;
-    if (request.params.size() > 0)
+    if (!request.params[0].isNull())
         timeout = request.params[0].get_int();
 
     CUpdatedBlock block;
@@ -252,7 +252,7 @@ UniValue waitforblock(const JSONRPCRequest& request)
 
     uint256 hash = uint256S(request.params[0].get_str());
 
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
         timeout = request.params[1].get_int();
 
     CUpdatedBlock block;
@@ -295,7 +295,7 @@ UniValue waitforblockheight(const JSONRPCRequest& request)
 
     int height = request.params[0].get_int();
 
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
         timeout = request.params[1].get_int();
 
     CUpdatedBlock block;
@@ -434,7 +434,7 @@ UniValue getrawmempool(const JSONRPCRequest& request)
         );
 
     bool fVerbose = false;
-    if (request.params.size() > 0)
+    if (!request.params[0].isNull())
         fVerbose = request.params[0].get_bool();
 
     return mempoolToJSON(fVerbose);
@@ -467,7 +467,7 @@ UniValue getmempoolancestors(const JSONRPCRequest& request)
     }
 
     bool fVerbose = false;
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
         fVerbose = request.params[1].get_bool();
 
     uint256 hash = ParseHashV(request.params[0], "parameter 1");
@@ -531,7 +531,7 @@ UniValue getmempooldescendants(const JSONRPCRequest& request)
     }
 
     bool fVerbose = false;
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
         fVerbose = request.params[1].get_bool();
 
     uint256 hash = ParseHashV(request.params[0], "parameter 1");
@@ -666,7 +666,7 @@ UniValue getblockheader(const JSONRPCRequest& request)
     uint256 hash(uint256S(strHash));
 
     bool fVerbose = true;
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
         fVerbose = request.params[1].get_bool();
 
     if (mapBlockIndex.count(hash) == 0)
@@ -741,7 +741,7 @@ UniValue getblock(const JSONRPCRequest& request)
     uint256 hash(uint256S(strHash));
 
     int verbosity = 1;
-    if (request.params.size() > 1) {
+    if (!request.params[1].isNull()) {
         if(request.params[1].isNum())
             verbosity = request.params[1].get_int();
         else
@@ -984,7 +984,7 @@ UniValue gettxout(const JSONRPCRequest& request)
     int n = request.params[1].get_int();
     COutPoint out(hash, n);
     bool fMempool = true;
-    if (request.params.size() > 2)
+    if (!request.params[2].isNull())
         fMempool = request.params[2].get_bool();
 
     Coin coin;
@@ -1037,9 +1037,9 @@ UniValue verifychain(const JSONRPCRequest& request)
 
     LOCK(cs_main);
 
-    if (request.params.size() > 0)
+    if (!request.params[0].isNull())
         nCheckLevel = request.params[0].get_int();
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
         nCheckDepth = request.params[1].get_int();
 
     return CVerifyDB().VerifyDB(Params(), pcoinsTip, nCheckLevel, nCheckDepth);
diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index daca32d25..7d292a463 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -102,7 +102,7 @@ UniValue getnetworkhashps(const JSONRPCRequest& request)
        );
 
     LOCK(cs_main);
-    return GetNetworkHashPS(request.params.size() > 0 ? request.params[0].get_int() : 120, request.params.size() > 1 ? request.params[1].get_int() : -1);
+    return GetNetworkHashPS(!request.params[0].isNull() ? request.params[0].get_int() : 120, !request.params[1].isNull() ? request.params[1].get_int() : -1);
 }
 
 UniValue generateBlocks(std::shared_ptr<CReserveScript> coinbaseScript, int nGenerate, uint64_t nMaxTries, bool keepScript)
@@ -172,7 +172,7 @@ UniValue generatetoaddress(const JSONRPCRequest& request)
 
     int nGenerate = request.params[0].get_int();
     uint64_t nMaxTries = 1000000;
-    if (request.params.size() > 2) {
+    if (!request.params[2].isNull()) {
         nMaxTries = request.params[2].get_int();
     }
 
@@ -374,7 +374,7 @@ UniValue getblocktemplate(const JSONRPCRequest& request)
     UniValue lpval = NullUniValue;
     std::set<std::string> setClientRules;
     int64_t nMaxVersionPreVB = -1;
-    if (request.params.size() > 0)
+    if (!request.params[0].isNull())
     {
         const UniValue& oparam = request.params[0].get_obj();
         const UniValue& modeval = find_value(oparam, "mode");
diff --git a/src/rpc/net.cpp b/src/rpc/net.cpp
index 090d9e448..b4d6795e6 100644
--- a/src/rpc/net.cpp
+++ b/src/rpc/net.cpp
@@ -310,7 +310,7 @@ UniValue getaddednodeinfo(const JSONRPCRequest& request)
 
     std::vector<AddedNodeInfo> vInfo = g_connman->GetAddedNodeInfo();
 
-    if (request.params.size() == 1) {
+    if (request.params.size() == 1 && !request.params[0].isNull()) {
         bool found = false;
         for (const AddedNodeInfo& info : vInfo) {
             if (info.strAddedNode == request.params[0].get_str()) {
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 10886fea9..b967f2dbf 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -137,7 +137,7 @@ UniValue getrawtransaction(const JSONRPCRequest& request)
 
     // Accept either a bool (true) or a num (>=1) to indicate verbose output.
     bool fVerbose = false;
-    if (request.params.size() > 1) {
+    if (!request.params[1].isNull()) {
         if (request.params[1].isNum()) {
             if (request.params[1].get_int() != 0) {
                 fVerbose = true;
@@ -211,7 +211,7 @@ UniValue gettxoutproof(const JSONRPCRequest& request)
     CBlockIndex* pblockindex = NULL;
 
     uint256 hashBlock;
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
     {
         hashBlock = uint256S(request.params[1].get_str());
         if (!mapBlockIndex.count(hashBlock))
@@ -412,7 +412,7 @@ UniValue createrawtransaction(const JSONRPCRequest& request)
         }
     }
 
-    if (request.params.size() > 3 && rbfOptIn != SignalsOptInRBF(rawTx)) {
+    if (!request.params[3].isNull() && rbfOptIn != SignalsOptInRBF(rawTx)) {
         throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter combination: Sequence number(s) contradict replaceable option");
     }
 
diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index 9f42b1f26..5abf32480 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -106,12 +106,12 @@ UniValue importprivkey(const JSONRPCRequest& request)
 
     std::string strSecret = request.params[0].get_str();
     std::string strLabel = "";
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
         strLabel = request.params[1].get_str();
 
     // Whether to perform rescan after import
     bool fRescan = true;
-    if (request.params.size() > 2)
+    if (!request.params[2].isNull())
         fRescan = request.params[2].get_bool();
 
     if (fRescan && fPruneMode)
@@ -245,12 +245,12 @@ UniValue importaddress(const JSONRPCRequest& request)
 
 
     std::string strLabel = "";
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
         strLabel = request.params[1].get_str();
 
     // Whether to perform rescan after import
     bool fRescan = true;
-    if (request.params.size() > 2)
+    if (!request.params[2].isNull())
         fRescan = request.params[2].get_bool();
 
     if (fRescan && fPruneMode)
@@ -258,7 +258,7 @@ UniValue importaddress(const JSONRPCRequest& request)
 
     // Whether to import a p2sh version, too
     bool fP2SH = false;
-    if (request.params.size() > 3)
+    if (!request.params[3].isNull())
         fP2SH = request.params[3].get_bool();
 
     LOCK2(cs_main, pwallet->cs_wallet);
@@ -410,12 +410,12 @@ UniValue importpubkey(const JSONRPCRequest& request)
 
 
     std::string strLabel = "";
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
         strLabel = request.params[1].get_str();
 
     // Whether to perform rescan after import
     bool fRescan = true;
-    if (request.params.size() > 2)
+    if (!request.params[2].isNull())
         fRescan = request.params[2].get_bool();
 
     if (fRescan && fPruneMode)
@@ -1028,7 +1028,7 @@ UniValue importmulti(const JSONRPCRequest& mainRequest)
     // clang-format off
     if (mainRequest.fHelp || mainRequest.params.size() < 1 || mainRequest.params.size() > 2)
         throw std::runtime_error(
-            "importmulti \"requests\" \"options\"\n\n"
+            "importmulti \"requests\" ( \"options\" )\n\n"
             "Import addresses/scripts (with private or public keys, redeem script (P2SH)), rescanning all addresses in one-shot-only (rescan can be disabled via options).\n\n"
             "Arguments:\n"
             "1. requests     (array, required) Data to be imported\n"
@@ -1071,7 +1071,7 @@ UniValue importmulti(const JSONRPCRequest& mainRequest)
     //Default options
     bool fRescan = true;
 
-    if (mainRequest.params.size() > 1) {
+    if (!mainRequest.params[1].isNull()) {
         const UniValue& options = mainRequest.params[1];
 
         if (options.exists("rescan")) {
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index f63ce1bb4..4275a9181 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -146,7 +146,7 @@ UniValue getnewaddress(const JSONRPCRequest& request)
 
     // Parse the account first so we don't generate a key if there's an error
     std::string strAccount;
-    if (request.params.size() > 0)
+    if (!request.params[0].isNull())
         strAccount = AccountFromValue(request.params[0]);
 
     if (!pwallet->IsLocked()) {
@@ -217,7 +217,7 @@ UniValue getrawchangeaddress(const JSONRPCRequest& request)
         return NullUniValue;
     }
 
-    if (request.fHelp || request.params.size() > 1)
+    if (request.fHelp || request.params.size() > 0)
         throw std::runtime_error(
             "getrawchangeaddress\n"
             "\nReturns a new Bitcoin address, for receiving change.\n"
@@ -496,7 +496,7 @@ UniValue listaddressgroupings(const JSONRPCRequest& request)
         return NullUniValue;
     }
 
-    if (request.fHelp)
+    if (request.fHelp || request.params.size() != 0)
         throw std::runtime_error(
             "listaddressgroupings\n"
             "\nLists groups of addresses which have had their common ownership\n"
@@ -641,7 +641,7 @@ UniValue getreceivedbyaddress(const JSONRPCRequest& request)
 
     // Minimum confirmations
     int nMinDepth = 1;
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
         nMinDepth = request.params[1].get_int();
 
     // Tally
@@ -692,7 +692,7 @@ UniValue getreceivedbyaccount(const JSONRPCRequest& request)
 
     // Minimum confirmations
     int nMinDepth = 1;
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
         nMinDepth = request.params[1].get_int();
 
     // Get the set of pub keys assigned to account
@@ -769,10 +769,10 @@ UniValue getbalance(const JSONRPCRequest& request)
     const std::string* account = account_param != "*" ? &account_param : nullptr;
 
     int nMinDepth = 1;
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
         nMinDepth = request.params[1].get_int();
     isminefilter filter = ISMINE_SPENDABLE;
-    if(request.params.size() > 2)
+    if(!request.params[2].isNull())
         if(request.params[2].get_bool())
             filter = filter | ISMINE_WATCH_ONLY;
 
@@ -975,7 +975,7 @@ UniValue sendmany(const JSONRPCRequest& request)
     std::string strAccount = AccountFromValue(request.params[0]);
     UniValue sendTo = request.params[1].get_obj();
     int nMinDepth = 1;
-    if (request.params.size() > 2)
+    if (!request.params[2].isNull())
         nMinDepth = request.params[2].get_int();
 
     CWalletTx wtx;
@@ -1222,16 +1222,16 @@ UniValue ListReceived(CWallet * const pwallet, const UniValue& params, bool fByA
 {
     // Minimum confirmations
     int nMinDepth = 1;
-    if (params.size() > 0)
+    if (!params[0].isNull())
         nMinDepth = params[0].get_int();
 
     // Whether to include empty accounts
     bool fIncludeEmpty = false;
-    if (params.size() > 1)
+    if (!params[1].isNull())
         fIncludeEmpty = params[1].get_bool();
 
     isminefilter filter = ISMINE_SPENDABLE;
-    if(params.size() > 2)
+    if(!params[2].isNull())
         if(params[2].get_bool())
             filter = filter | ISMINE_WATCH_ONLY;
 
@@ -1593,16 +1593,16 @@ UniValue listtransactions(const JSONRPCRequest& request)
     LOCK2(cs_main, pwallet->cs_wallet);
 
     std::string strAccount = "*";
-    if (request.params.size() > 0)
+    if (!request.params[0].isNull())
         strAccount = request.params[0].get_str();
     int nCount = 10;
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
         nCount = request.params[1].get_int();
     int nFrom = 0;
-    if (request.params.size() > 2)
+    if (!request.params[2].isNull())
         nFrom = request.params[2].get_int();
     isminefilter filter = ISMINE_SPENDABLE;
-    if(request.params.size() > 3)
+    if(!request.params[3].isNull())
         if(request.params[3].get_bool())
             filter = filter | ISMINE_WATCH_ONLY;
 
@@ -1742,7 +1742,7 @@ UniValue listsinceblock(const JSONRPCRequest& request)
         return NullUniValue;
     }
 
-    if (request.fHelp)
+    if (request.fHelp || request.params.size() > 3)
         throw std::runtime_error(
             "listsinceblock ( \"blockhash\" target_confirmations include_watchonly)\n"
             "\nGet all transactions in blocks since block [blockhash], or all transactions if omitted\n"
@@ -1789,7 +1789,7 @@ UniValue listsinceblock(const JSONRPCRequest& request)
     int target_confirms = 1;
     isminefilter filter = ISMINE_SPENDABLE;
 
-    if (request.params.size() > 0)
+    if (!request.params[0].isNull())
     {
         uint256 blockId;
 
@@ -1808,7 +1808,7 @@ UniValue listsinceblock(const JSONRPCRequest& request)
         }
     }
 
-    if (request.params.size() > 1)
+    if (!request.params[1].isNull())
     {
         target_confirms = request.params[1].get_int();
 
@@ -1900,7 +1900,7 @@ UniValue gettransaction(const JSONRPCRequest& request)
     hash.SetHex(request.params[0].get_str());
 
     isminefilter filter = ISMINE_SPENDABLE;
-    if(request.params.size() > 1)
+    if(!request.params[1].isNull())
         if(request.params[1].get_bool())
             filter = filter | ISMINE_WATCH_ONLY;
 
@@ -2022,7 +2022,7 @@ UniValue keypoolrefill(const JSONRPCRequest& request)
 
     // 0 is interpreted by TopUpKeyPool() as the default keypool size given by -keypool
     unsigned int kpSize = 0;
-    if (request.params.size() > 0) {
+    if (!request.params[0].isNull()) {
         if (request.params[0].get_int() < 0)
             throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, expected valid size.");
         kpSize = (unsigned int)request.params[0].get_int();
@@ -2615,7 +2615,7 @@ UniValue listunspent(const JSONRPCRequest& request)
     CAmount nMinimumSumAmount = MAX_MONEY;
     uint64_t nMaximumCount = 0;
 
-    if (request.params.size() > 4) {
+    if (!request.params[4].isNull()) {
         const UniValue& options = request.params[4].get_obj();
 
         if (options.exists("minimumAmount"))
@@ -2684,7 +2684,7 @@ UniValue fundrawtransaction(const JSONRPCRequest& request)
         return NullUniValue;
     }
 
-    if (request.fHelp || request.params.size() < 1 || request.params.size() > 3)
+    if (request.fHelp || request.params.size() < 1 || request.params.size() > 2)
         throw std::runtime_error(
                             "fundrawtransaction \"hexstring\" ( options )\n"
                             "\nAdd inputs to a transaction until it has enough in value to meet its out value.\n"
@@ -2746,7 +2746,7 @@ UniValue fundrawtransaction(const JSONRPCRequest& request)
     UniValue subtractFeeFromOutputs;
     std::set<int> setSubtractFeeFromOutputs;
 
-    if (request.params.size() > 1) {
+    if (!request.params[1].isNull()) {
       if (request.params[1].type() == UniValue::VBOOL) {
         // backward compatibility bool only fallback
         coinControl.fAllowWatchOnly = request.params[1].get_bool();
@@ -2911,7 +2911,7 @@ UniValue bumpfee(const JSONRPCRequest& request)
     CAmount totalFee = 0;
     CCoinControl coin_control;
     coin_control.signalRbf = true;
-    if (request.params.size() > 1) {
+    if (!request.params[1].isNull()) {
         UniValue options = request.params[1];
         RPCTypeCheckObj(options,
             {