diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index da5984a245..8f116a05ef 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -397,7 +397,7 @@ static RPCHelpMan syncwithvalidationinterfacequeue()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     SyncWithValidationInterfaceQueue();
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -1056,11 +1056,11 @@ static RPCHelpMan gettxout()
         LOCK(mempool.cs);
         CCoinsViewMemPool view(coins_view, mempool);
         if (!view.GetCoin(out, coin) || mempool.isSpent(out)) {
-            return NullUniValue;
+            return UniValue::VNULL;
         }
     } else {
         if (!coins_view->GetCoin(out, coin)) {
-            return NullUniValue;
+            return UniValue::VNULL;
         }
     }
 
@@ -1498,7 +1498,7 @@ static RPCHelpMan preciousblock()
         throw JSONRPCError(RPC_DATABASE_ERROR, state.ToString());
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -1539,7 +1539,7 @@ static RPCHelpMan invalidateblock()
         throw JSONRPCError(RPC_DATABASE_ERROR, state.ToString());
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -1579,7 +1579,7 @@ static RPCHelpMan reconsiderblock()
         throw JSONRPCError(RPC_DATABASE_ERROR, state.ToString());
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -2098,7 +2098,7 @@ static RPCHelpMan scantxoutset()
         CoinsViewScanReserver reserver;
         if (reserver.reserve()) {
             // no scan in progress
-            return NullUniValue;
+            return UniValue::VNULL;
         }
         result.pushKV("progress", g_scan_progress.load());
         return result;
diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index ea6db1e9a0..2902b35865 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -476,7 +476,7 @@ static RPCHelpMan prioritisetransaction()
 static UniValue BIP22ValidationResult(const BlockValidationState& state)
 {
     if (state.IsValid())
-        return NullUniValue;
+        return UniValue::VNULL;
 
     if (state.IsError())
         throw JSONRPCError(RPC_VERIFY_ERROR, state.ToString());
@@ -1040,7 +1040,7 @@ static RPCHelpMan submitheader()
 
     BlockValidationState state;
     chainman.ProcessNewBlockHeaders({h}, state);
-    if (state.IsValid()) return NullUniValue;
+    if (state.IsValid()) return UniValue::VNULL;
     if (state.IsError()) {
         throw JSONRPCError(RPC_VERIFY_ERROR, state.ToString());
     }
diff --git a/src/rpc/net.cpp b/src/rpc/net.cpp
index d88861a0c4..76cf8d8ea9 100644
--- a/src/rpc/net.cpp
+++ b/src/rpc/net.cpp
@@ -84,7 +84,7 @@ static RPCHelpMan ping()
 
     // Request that each node send a ping during next message processing pass
     peerman.SendPings();
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -304,7 +304,7 @@ static RPCHelpMan addnode()
     {
         CAddress addr;
         connman.OpenNetworkConnection(addr, false, nullptr, strNode.c_str(), ConnectionType::MANUAL);
-        return NullUniValue;
+        return UniValue::VNULL;
     }
 
     if (strCommand == "add")
@@ -320,7 +320,7 @@ static RPCHelpMan addnode()
         }
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -423,7 +423,7 @@ static RPCHelpMan disconnectnode()
         throw JSONRPCError(RPC_CLIENT_NODE_NOT_CONNECTED, "Node not found in connected nodes");
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -745,7 +745,7 @@ static RPCHelpMan setban()
             throw JSONRPCError(RPC_CLIENT_INVALID_IP_OR_SUBNET, "Error: Unban failed. Requested address/subnet was not previously manually banned.");
         }
     }
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -819,7 +819,7 @@ static RPCHelpMan clearbanned()
 
     node.banman->ClearBanned();
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
diff --git a/src/rpc/node.cpp b/src/rpc/node.cpp
index 5475662b82..605ebc15a7 100644
--- a/src/rpc/node.cpp
+++ b/src/rpc/node.cpp
@@ -65,7 +65,7 @@ static RPCHelpMan setmocktime()
         }
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -85,7 +85,7 @@ static RPCHelpMan invokedisallowedsyscall()
                 throw std::runtime_error("invokedisallowedsyscall is used for testing only.");
             }
             TestDisallowedSandboxCall();
-            return NullUniValue;
+            return UniValue::VNULL;
         },
     };
 }
@@ -118,7 +118,7 @@ static RPCHelpMan mockscheduler()
     CHECK_NONFATAL(node_context->scheduler);
     node_context->scheduler->MockForward(std::chrono::seconds(delta_seconds));
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
diff --git a/src/test/fuzz/parse_univalue.cpp b/src/test/fuzz/parse_univalue.cpp
index c7a76aa52f..0cc210f26f 100644
--- a/src/test/fuzz/parse_univalue.cpp
+++ b/src/test/fuzz/parse_univalue.cpp
@@ -26,7 +26,7 @@ FUZZ_TARGET_INIT(parse_univalue, initialize_parse_univalue)
             return ParseNonRFCJSONValue(random_string);
         } catch (const std::runtime_error&) {
             valid = false;
-            return NullUniValue;
+            return UniValue{};
         }
     }();
     if (!valid) {
diff --git a/src/wallet/rpc/addresses.cpp b/src/wallet/rpc/addresses.cpp
index 9428d049de..2a6eb96871 100644
--- a/src/wallet/rpc/addresses.cpp
+++ b/src/wallet/rpc/addresses.cpp
@@ -34,7 +34,7 @@ RPCHelpMan getnewaddress()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LOCK(pwallet->cs_wallet);
 
@@ -86,7 +86,7 @@ RPCHelpMan getrawchangeaddress()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LOCK(pwallet->cs_wallet);
 
@@ -131,7 +131,7 @@ RPCHelpMan setlabel()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LOCK(pwallet->cs_wallet);
 
@@ -148,7 +148,7 @@ RPCHelpMan setlabel()
         pwallet->SetAddressBook(dest, label, "send");
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -181,7 +181,7 @@ RPCHelpMan listaddressgroupings()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -252,7 +252,7 @@ RPCHelpMan addmultisigaddress()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LegacyScriptPubKeyMan& spk_man = EnsureLegacyScriptPubKeyMan(*pwallet);
 
@@ -327,7 +327,7 @@ RPCHelpMan keypoolrefill()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     if (pwallet->IsLegacy() && pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
         throw JSONRPCError(RPC_WALLET_ERROR, "Error: Private keys are disabled for this wallet");
@@ -350,7 +350,7 @@ RPCHelpMan keypoolrefill()
         throw JSONRPCError(RPC_WALLET_ERROR, "Error refreshing keypool.");
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -374,14 +374,14 @@ RPCHelpMan newkeypool()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LOCK(pwallet->cs_wallet);
 
     LegacyScriptPubKeyMan& spk_man = EnsureLegacyScriptPubKeyMan(*pwallet, true);
     spk_man.NewKeyPool();
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -548,7 +548,7 @@ RPCHelpMan getaddressinfo()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LOCK(pwallet->cs_wallet);
 
@@ -658,7 +658,7 @@ RPCHelpMan getaddressesbylabel()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LOCK(pwallet->cs_wallet);
 
@@ -721,7 +721,7 @@ RPCHelpMan listlabels()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LOCK(pwallet->cs_wallet);
 
@@ -763,7 +763,7 @@ RPCHelpMan walletdisplayaddress()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
         {
             std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
-            if (!wallet) return NullUniValue;
+            if (!wallet) return UniValue::VNULL;
             CWallet* const pwallet = wallet.get();
 
             LOCK(pwallet->cs_wallet);
diff --git a/src/wallet/rpc/backup.cpp b/src/wallet/rpc/backup.cpp
index 62aba4f3f2..57c3bcc68b 100644
--- a/src/wallet/rpc/backup.cpp
+++ b/src/wallet/rpc/backup.cpp
@@ -124,7 +124,7 @@ RPCHelpMan importprivkey()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     if (pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
         throw JSONRPCError(RPC_WALLET_ERROR, "Cannot import private keys to a wallet with private keys disabled");
@@ -192,7 +192,7 @@ RPCHelpMan importprivkey()
         RescanWallet(*pwallet, reserver);
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -229,7 +229,7 @@ RPCHelpMan importaddress()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     EnsureLegacyScriptPubKeyMan(*pwallet, true);
 
@@ -299,7 +299,7 @@ RPCHelpMan importaddress()
         }
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -317,7 +317,7 @@ RPCHelpMan importprunedfunds()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     CMutableTransaction tx;
     if (!DecodeHexTx(tx, request.params[0].get_str())) {
@@ -352,7 +352,7 @@ RPCHelpMan importprunedfunds()
     CTransactionRef tx_ref = MakeTransactionRef(tx);
     if (pwallet->IsMine(*tx_ref)) {
         pwallet->AddToWallet(std::move(tx_ref), TxStateConfirmed{merkleBlock.header.GetHash(), height, static_cast<int>(txnIndex)});
-        return NullUniValue;
+        return UniValue::VNULL;
     }
 
     throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "No addresses in wallet correspond to included transaction");
@@ -376,7 +376,7 @@ RPCHelpMan removeprunedfunds()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LOCK(pwallet->cs_wallet);
 
@@ -393,7 +393,7 @@ RPCHelpMan removeprunedfunds()
         throw JSONRPCError(RPC_INVALID_PARAMETER, "Transaction does not exist in wallet.");
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -425,7 +425,7 @@ RPCHelpMan importpubkey()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     EnsureLegacyScriptPubKeyMan(*pwallet, true);
 
@@ -480,7 +480,7 @@ RPCHelpMan importpubkey()
         }
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -506,7 +506,7 @@ RPCHelpMan importwallet()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     EnsureLegacyScriptPubKeyMan(*pwallet, true);
 
@@ -637,7 +637,7 @@ RPCHelpMan importwallet()
     if (!fGood)
         throw JSONRPCError(RPC_WALLET_ERROR, "Error adding some keys/scripts to wallet");
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -661,7 +661,7 @@ RPCHelpMan dumpprivkey()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     const LegacyScriptPubKeyMan& spk_man = EnsureConstLegacyScriptPubKeyMan(*pwallet);
 
@@ -711,7 +711,7 @@ RPCHelpMan dumpwallet()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     const CWallet& wallet = *pwallet;
     const LegacyScriptPubKeyMan& spk_man = EnsureConstLegacyScriptPubKeyMan(wallet);
@@ -1328,7 +1328,7 @@ RPCHelpMan importmulti()
         [&](const RPCHelpMan& self, const JSONRPCRequest& mainRequest) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(mainRequest);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
     CWallet& wallet{*pwallet};
 
     // Make sure the results are valid at least up to the most recent block
@@ -1636,7 +1636,7 @@ RPCHelpMan importdescriptors()
         [&](const RPCHelpMan& self, const JSONRPCRequest& main_request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(main_request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
     CWallet& wallet{*pwallet};
 
     // Make sure the results are valid at least up to the most recent block
@@ -1771,7 +1771,7 @@ RPCHelpMan listdescriptors()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> wallet = GetWalletForJSONRPCRequest(request);
-    if (!wallet) return NullUniValue;
+    if (!wallet) return UniValue::VNULL;
 
     if (!wallet->IsWalletFlagSet(WALLET_FLAG_DESCRIPTORS)) {
         throw JSONRPCError(RPC_WALLET_ERROR, "listdescriptors is not available for non-descriptor wallets");
@@ -1840,7 +1840,7 @@ RPCHelpMan backupwallet()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -1853,7 +1853,7 @@ RPCHelpMan backupwallet()
         throw JSONRPCError(RPC_WALLET_ERROR, "Error: Wallet backup failed!");
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
diff --git a/src/wallet/rpc/coins.cpp b/src/wallet/rpc/coins.cpp
index a9fff95882..9e992294ff 100644
--- a/src/wallet/rpc/coins.cpp
+++ b/src/wallet/rpc/coins.cpp
@@ -103,7 +103,7 @@ RPCHelpMan getreceivedbyaddress()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -144,7 +144,7 @@ RPCHelpMan getreceivedbylabel()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -184,7 +184,7 @@ RPCHelpMan getbalance()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -223,7 +223,7 @@ RPCHelpMan getunconfirmedbalance()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -282,7 +282,7 @@ RPCHelpMan lockunspent()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -407,7 +407,7 @@ RPCHelpMan listlockunspent()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LOCK(pwallet->cs_wallet);
 
@@ -459,7 +459,7 @@ RPCHelpMan getbalances()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> rpc_wallet = GetWalletForJSONRPCRequest(request);
-    if (!rpc_wallet) return NullUniValue;
+    if (!rpc_wallet) return UniValue::VNULL;
     const CWallet& wallet = *rpc_wallet;
 
     // Make sure the results are valid at least up to the most recent block
@@ -559,7 +559,7 @@ RPCHelpMan listunspent()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     int nMinDepth = 1;
     if (!request.params[0].isNull()) {
diff --git a/src/wallet/rpc/encrypt.cpp b/src/wallet/rpc/encrypt.cpp
index 931c64ca06..a68f52a718 100644
--- a/src/wallet/rpc/encrypt.cpp
+++ b/src/wallet/rpc/encrypt.cpp
@@ -32,7 +32,7 @@ RPCHelpMan walletpassphrase()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
-    if (!wallet) return NullUniValue;
+    if (!wallet) return UniValue::VNULL;
     CWallet* const pwallet = wallet.get();
 
     int64_t nSleepTime;
@@ -98,7 +98,7 @@ RPCHelpMan walletpassphrase()
         }
     }, nSleepTime);
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -120,7 +120,7 @@ RPCHelpMan walletpassphrasechange()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LOCK(pwallet->cs_wallet);
 
@@ -146,7 +146,7 @@ RPCHelpMan walletpassphrasechange()
         throw JSONRPCError(RPC_WALLET_PASSPHRASE_INCORRECT, "Error: The wallet passphrase entered was incorrect.");
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -173,7 +173,7 @@ RPCHelpMan walletlock()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LOCK(pwallet->cs_wallet);
 
@@ -184,7 +184,7 @@ RPCHelpMan walletlock()
     pwallet->Lock();
     pwallet->nRelockTime = 0;
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -217,7 +217,7 @@ RPCHelpMan encryptwallet()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LOCK(pwallet->cs_wallet);
 
diff --git a/src/wallet/rpc/signmessage.cpp b/src/wallet/rpc/signmessage.cpp
index 438d290030..ae4bd4fbc5 100644
--- a/src/wallet/rpc/signmessage.cpp
+++ b/src/wallet/rpc/signmessage.cpp
@@ -36,7 +36,7 @@ RPCHelpMan signmessage()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
         {
             const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-            if (!pwallet) return NullUniValue;
+            if (!pwallet) return UniValue::VNULL;
 
             LOCK(pwallet->cs_wallet);
 
diff --git a/src/wallet/rpc/spend.cpp b/src/wallet/rpc/spend.cpp
index 83e23497cb..b5472efa61 100644
--- a/src/wallet/rpc/spend.cpp
+++ b/src/wallet/rpc/spend.cpp
@@ -261,7 +261,7 @@ RPCHelpMan sendtoaddress()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -367,7 +367,7 @@ RPCHelpMan sendmany()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -422,7 +422,7 @@ RPCHelpMan settxfee()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LOCK(pwallet->cs_wallet);
 
@@ -805,7 +805,7 @@ RPCHelpMan fundrawtransaction()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     RPCTypeCheck(request.params, {UniValue::VSTR, UniValueType(), UniValue::VBOOL});
 
@@ -895,7 +895,7 @@ RPCHelpMan signrawtransactionwithwallet()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VARR, UniValue::VSTR}, true);
 
@@ -992,7 +992,7 @@ static RPCHelpMan bumpfee_helper(std::string method_name)
         [want_psbt](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     if (pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) && !want_psbt) {
         throw JSONRPCError(RPC_WALLET_ERROR, "bumpfee is not available with wallets that have private keys disabled. Use psbtbumpfee instead.");
@@ -1209,7 +1209,7 @@ RPCHelpMan send()
             );
 
             std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-            if (!pwallet) return NullUniValue;
+            if (!pwallet) return UniValue::VNULL;
 
             UniValue options{request.params[4].isNull() ? UniValue::VOBJ : request.params[4]};
             InterpretFeeEstimationInstructions(/*conf_target=*/request.params[1], /*estimate_mode=*/request.params[2], /*fee_rate=*/request.params[3], options);
@@ -1314,7 +1314,7 @@ RPCHelpMan sendall()
             );
 
             std::shared_ptr<CWallet> const pwallet{GetWalletForJSONRPCRequest(request)};
-            if (!pwallet) return NullUniValue;
+            if (!pwallet) return UniValue::VNULL;
             // Make sure the results are valid at least up to the most recent block
             // the user could have gotten from another RPC command prior to now
             pwallet->BlockUntilSyncedToCurrentChain();
@@ -1490,7 +1490,7 @@ RPCHelpMan walletprocesspsbt()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     const CWallet& wallet{*pwallet};
     // Make sure the results are valid at least up to the most recent block
@@ -1617,7 +1617,7 @@ RPCHelpMan walletcreatefundedpsbt()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     CWallet& wallet{*pwallet};
     // Make sure the results are valid at least up to the most recent block
diff --git a/src/wallet/rpc/transactions.cpp b/src/wallet/rpc/transactions.cpp
index 0b52dcc001..9c8003d6d7 100644
--- a/src/wallet/rpc/transactions.cpp
+++ b/src/wallet/rpc/transactions.cpp
@@ -236,7 +236,7 @@ RPCHelpMan listreceivedbyaddress()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -281,7 +281,7 @@ RPCHelpMan listreceivedbylabel()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -471,7 +471,7 @@ RPCHelpMan listtransactions()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -586,7 +586,7 @@ RPCHelpMan listsinceblock()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     const CWallet& wallet = *pwallet;
     // Make sure the results are valid at least up to the most recent block
@@ -727,7 +727,7 @@ RPCHelpMan gettransaction()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -800,7 +800,7 @@ RPCHelpMan abandontransaction()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -817,7 +817,7 @@ RPCHelpMan abandontransaction()
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Transaction not eligible for abandonment");
     }
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -845,7 +845,7 @@ RPCHelpMan rescanblockchain()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
     CWallet& wallet{*pwallet};
 
     // Make sure the results are valid at least up to the most recent block
@@ -925,7 +925,7 @@ RPCHelpMan abortrescan()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     if (!pwallet->IsScanning() || pwallet->IsAbortingRescan()) return false;
     pwallet->AbortRescan();
diff --git a/src/wallet/rpc/wallet.cpp b/src/wallet/rpc/wallet.cpp
index be1b6de7ac..b474236e58 100644
--- a/src/wallet/rpc/wallet.cpp
+++ b/src/wallet/rpc/wallet.cpp
@@ -68,7 +68,7 @@ static RPCHelpMan getwalletinfo()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     // Make sure the results are valid at least up to the most recent block
     // the user could have gotten from another RPC command prior to now
@@ -267,7 +267,7 @@ static RPCHelpMan setwalletflag()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     std::string flag_str = request.params[0].get_str();
     bool value = request.params[1].isNull() || request.params[1].get_bool();
@@ -480,7 +480,7 @@ static RPCHelpMan sethdseed()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     LegacyScriptPubKeyMan& spk_man = EnsureLegacyScriptPubKeyMan(*pwallet, true);
 
@@ -521,7 +521,7 @@ static RPCHelpMan sethdseed()
     spk_man.SetHDSeed(master_pub_key);
     if (flush_key_pool) spk_man.NewKeyPool();
 
-    return NullUniValue;
+    return UniValue::VNULL;
 },
     };
 }
@@ -551,7 +551,7 @@ static RPCHelpMan upgradewallet()
         [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
 {
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
-    if (!pwallet) return NullUniValue;
+    if (!pwallet) return UniValue::VNULL;
 
     RPCTypeCheck(request.params, {UniValue::VNUM}, true);