Add psbt_version to PSBT RPCs and default to v2

diff --git a/src/psbt.h b/src/psbt.h
index c5bbff89..9e514f2e 100644
--- a/src/psbt.h
+++ b/src/psbt.h
@@ -92,7 +92,7 @@ static constexpr uint8_t PSBT_SEPARATOR = 0x00;
 const std::streamsize MAX_FILE_SIZE_PSBT = 100000000; // 100 MB
 
 // PSBT version number
-static constexpr uint32_t PSBT_HIGHEST_VERSION = 0;
+static constexpr uint32_t PSBT_HIGHEST_VERSION = 2;
 
 /** A structure for PSBT proprietary types */
 struct PSBTProprietary
diff --git a/src/rpc/client.cpp b/src/rpc/client.cpp
index 8d3e551d..a28543fb 100644
--- a/src/rpc/client.cpp
+++ b/src/rpc/client.cpp
@@ -208,6 +208,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "walletcreatefundedpsbt", 3, "max_tx_weight"},
     { "walletcreatefundedpsbt", 4, "bip32derivs" },
     { "walletcreatefundedpsbt", 5, "version" },
+    { "walletcreatefundedpsbt", 6, "psbt_version" },
     { "walletprocesspsbt", 0, "psbt", ParamFormat::STRING },
     { "walletprocesspsbt", 1, "sign" },
     { "walletprocesspsbt", 2, "sighashtype", ParamFormat::STRING },
@@ -223,12 +224,14 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "createpsbt", 2, "locktime" },
     { "createpsbt", 3, "replaceable" },
     { "createpsbt", 4, "version" },
+    { "createpsbt", 5, "psbt_version" },
     { "combinepsbt", 0, "txs"},
     { "joinpsbts", 0, "txs"},
     { "finalizepsbt", 0, "psbt", ParamFormat::STRING },
     { "finalizepsbt", 1, "extract"},
     { "converttopsbt", 1, "permitsigdata"},
     { "converttopsbt", 2, "iswitness"},
+    { "converttopsbt", 3, "psbt_version"},
     { "gettxout", 1, "n" },
     { "gettxout", 2, "include_mempool" },
     { "gettxoutproof", 0, "txids" },
@@ -328,6 +331,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "psbtbumpfee", 1, "replaceable"},
     { "psbtbumpfee", 1, "outputs"},
     { "psbtbumpfee", 1, "original_change_index"},
+    { "psbtbumpfee", 1, "psbt_version"},
     { "logging", 0, "include" },
     { "logging", 1, "exclude" },
     { "disconnectnode", 1, "nodeid" },
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 539c24cd..396768ed 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -1685,7 +1685,12 @@ static RPCMethod createpsbt()
                 "Implements the Creator role.\n"
                 "Note that the transaction's inputs are not signed, and\n"
                 "it is not stored in the wallet or transmitted to the network.\n",
-                CreateTxDoc(),
+                Cat<std::vector<RPCArg>>(
+                    CreateTxDoc(),
+                    {
+                        {"psbt_version", RPCArg::Type::NUM, RPCArg::Default{2}, "The PSBT version number to use."},
+                    }
+                ),
                 RPCResult{
                     RPCResult::Type::STR, "", "The resulting raw transaction (base64-encoded string)"
                 },
@@ -1694,7 +1699,6 @@ static RPCMethod createpsbt()
                 },
         [](const RPCMethod& self, const JSONRPCRequest& request) -> UniValue
 {
-
     std::optional<bool> rbf;
     if (!request.params[3].isNull()) {
         rbf = request.params[3].get_bool();
@@ -1702,7 +1706,14 @@ static RPCMethod createpsbt()
     CMutableTransaction rawTx = ConstructTransaction(request.params[0], request.params[1], request.params[2], rbf, self.Arg<uint32_t>("version"));
 
     // Make a blank psbt
-    PartiallySignedTransaction psbtx(rawTx);
+    uint32_t psbt_version = 2;
+    if (!request.params[5].isNull()) {
+        psbt_version = request.params[5].getInt<uint32_t>();
+    }
+    if (psbt_version != 2 && psbt_version != 0) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "The PSBT version can only be 2 or 0");
+    }
+    PartiallySignedTransaction psbtx(rawTx, psbt_version);
 
     // Serialize the PSBT
     DataStream ssTx{};
@@ -1730,6 +1741,7 @@ static RPCMethod converttopsbt()
                         "This boolean should reflect whether the transaction has inputs\n"
                         "(e.g. fully valid, or on-chain transactions), if known by the caller."
                     },
+                    {"psbt_version", RPCArg::Type::NUM, RPCArg::Default{2}, "The PSBT version number to use."},
                 },
                 RPCResult{
                     RPCResult::Type::STR, "", "The resulting raw transaction (base64-encoded string)"
@@ -1763,7 +1775,14 @@ static RPCMethod converttopsbt()
     }
 
     // Make a blank psbt
-    PartiallySignedTransaction psbtx(tx);
+    uint32_t psbt_version = 2;
+    if (!request.params[3].isNull()) {
+        psbt_version = request.params[3].getInt<uint32_t>();
+    }
+    if (psbt_version != 2 && psbt_version != 0) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "The PSBT version can only be 2 or 0");
+    }
+    PartiallySignedTransaction psbtx(tx, psbt_version);
 
     // Serialize the PSBT
     DataStream ssTx{};
diff --git a/src/wallet/rpc/spend.cpp b/src/wallet/rpc/spend.cpp
index ef59c1f8..b6cdc860 100644
--- a/src/wallet/rpc/spend.cpp
+++ b/src/wallet/rpc/spend.cpp
@@ -109,7 +109,7 @@ static UniValue FinishTransaction(const std::shared_ptr<CWallet> pwallet, const
     }
 
     // Make a blank psbt
-    PartiallySignedTransaction psbtx(rawTx);
+    PartiallySignedTransaction psbtx(rawTx, /*version=*/2);
 
     // First fill transaction with our data without signing,
     // so external signers are not asked to sign more than once.
@@ -979,6 +979,7 @@ static RPCMethod bumpfee_helper(std::string method_name)
         {
             {"txid", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The txid to be bumped"},
             {"options", RPCArg::Type::OBJ_NAMED_PARAMS, RPCArg::Optional::OMITTED, "",
+                Cat(
                 {
                     {"conf_target", RPCArg::Type::NUM, RPCArg::DefaultHint{"wallet -txconfirmtarget"}, "Confirmation target in blocks\n"},
                     {"fee_rate", RPCArg::Type::AMOUNT, RPCArg::DefaultHint{"not set, fall back to wallet fee estimation"},
@@ -1007,6 +1008,8 @@ static RPCMethod bumpfee_helper(std::string method_name)
                                                                                                                             "original change output. The change output’s amount can increase if bumping the transaction "
                                                                                                                             "adds new inputs, otherwise it will decrease. Cannot be used in combination with the 'outputs' option."},
                 },
+                want_psbt ? std::vector<RPCArg>{{"psbt_version", RPCArg::Type::NUM, RPCArg::Default(2), "The PSBT version number to use."}} : std::vector<RPCArg>()
+                ),
                 RPCArgOptions{.oneline_description="options"}},
         },
         RPCResult{
@@ -1045,6 +1048,8 @@ static RPCMethod bumpfee_helper(std::string method_name)
 
     std::optional<uint32_t> original_change_index;
 
+    uint32_t psbt_version = 2;
+
     if (!request.params[1].isNull()) {
         UniValue options = request.params[1];
         RPCTypeCheckObj(options,
@@ -1056,6 +1061,7 @@ static RPCMethod bumpfee_helper(std::string method_name)
                 {"estimate_mode", UniValueType(UniValue::VSTR)},
                 {"outputs", UniValueType()}, // will be checked by AddOutputs()
                 {"original_change_index", UniValueType(UniValue::VNUM)},
+                {"psbt_version", UniValueType(UniValue::VNUM)},
             },
             true, true);
 
@@ -1083,6 +1089,13 @@ static RPCMethod bumpfee_helper(std::string method_name)
         if (options.exists("original_change_index")) {
             original_change_index = options["original_change_index"].getInt<uint32_t>();
         }
+
+        if (options.exists("psbt_version")) {
+            psbt_version = options["psbt_version"].getInt<uint32_t>();
+        }
+        if (psbt_version != 2 && psbt_version != 0) {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "The PSBT version can only be 2 or 0");
+        }
     }
 
     // Make sure the results are valid at least up to the most recent block
@@ -1136,7 +1149,7 @@ static RPCMethod bumpfee_helper(std::string method_name)
 
         result.pushKV("txid", txid.GetHex());
     } else {
-        PartiallySignedTransaction psbtx(mtx);
+        PartiallySignedTransaction psbtx(mtx, psbt_version);
         bool complete = false;
         const auto err{pwallet->FillPSBT(psbtx, {.sign = false, .bip32_derivs = true}, complete)};
         CHECK_NONFATAL(!err);
@@ -1723,6 +1736,7 @@ RPCMethod walletcreatefundedpsbt()
                         RPCArgOptions{.oneline_description="options"}},
                     {"bip32derivs", RPCArg::Type::BOOL, RPCArg::Default{true}, "Include BIP 32 derivation paths for public keys if we know them"},
                     {"version", RPCArg::Type::NUM, RPCArg::Default{DEFAULT_WALLET_TX_VERSION}, "Transaction version"},
+                    {"psbt_version", RPCArg::Type::NUM, RPCArg::Default(2), "The PSBT version number to use."},
                 },
                 RPCResult{
                     RPCResult::Type::OBJ, "", "",
@@ -1772,7 +1786,15 @@ RPCMethod walletcreatefundedpsbt()
     auto txr = FundTransaction(wallet, rawTx, recipients, options, coin_control, /*override_min_fee=*/true);
 
     // Make a blank psbt
-    PartiallySignedTransaction psbtx(CMutableTransaction(*txr.tx));
+    uint32_t psbt_version = 2;
+    if (!request.params[6].isNull()) {
+        psbt_version = request.params[6].getInt<int>();
+    }
+    if (psbt_version != 2 && psbt_version != 0) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "The PSBT version can only be 2 or 0");
+    }
+
+    PartiallySignedTransaction psbtx(CMutableTransaction(*txr.tx), psbt_version);
 
     // Fill transaction with out data but don't sign
     bool bip32derivs = request.params[4].isNull() ? true : request.params[4].get_bool();
diff --git a/test/functional/data/rpc_psbt.json b/test/functional/data/rpc_psbt.json
index fd46312a..8c049b8c 100644
--- a/test/functional/data/rpc_psbt.json
+++ b/test/functional/data/rpc_psbt.json
@@ -180,6 +180,7 @@
                     "bcrt1qqzh2ngh97ru8dfvgma25d6r595wcwqy0cee4cc": 1
                 }
             ],
+            "version": 0,
             "result" : "cHNidP8BAJoCAAAAAljoeiG1ba8MI76OcHBFbDNvfLqlyHV5JPVFiHuyq911AAAAAAD/////g40EJ9DsZQpoqka7CwmK6kQiwHGyyng1Kgd5WdB86h0BAAAAAP////8CcKrwCAAAAAAWABTYXCtx0AYLCcmIauuBXlCZHdoSTQDh9QUAAAAAFgAUAK6pouXw+HaliN9VRuh0LR2HAI8AAAAAAAAAAAA="
         }
     ],
diff --git a/test/functional/rpc_psbt.py b/test/functional/rpc_psbt.py
index cd47f61a..3c3e7288 100755
--- a/test/functional/rpc_psbt.py
+++ b/test/functional/rpc_psbt.py
@@ -37,6 +37,7 @@ from test_framework.psbt import (
     PSBT_IN_WITNESS_UTXO,
     PSBT_OUT_MUSIG2_PARTICIPANT_PUBKEYS,
     PSBT_OUT_TAP_TREE,
+    PSBT_OUT_SCRIPT,
 )
 from test_framework.script import CScript, OP_TRUE, SIGHASH_ALL, SIGHASH_ANYONECANPAY
 from test_framework.script_util import MIN_STANDARD_TX_NONWITNESS_SIZE
@@ -110,9 +111,7 @@ class PSBTTest(BitcoinTestFramework):
 
         # Modify the raw transaction by changing the output address, so the signature is no longer valid
         signed_psbt_obj = PSBT.from_base64(signed_psbt)
-        substitute_addr = wallet.getnewaddress()
-        raw = wallet.createrawtransaction([{"txid": utxos[0]["txid"], "vout": utxos[0]["vout"]}], [{substitute_addr: 0.9999}])
-        signed_psbt_obj.g.map[PSBT_GLOBAL_UNSIGNED_TX] = bytes.fromhex(raw)
+        signed_psbt_obj.o[0].map[PSBT_OUT_SCRIPT] = CScript([OP_TRUE])
 
         # Check that the walletprocesspsbt call succeeds but also recognizes that the transaction is not complete
         signed_psbt_incomplete = wallet.walletprocesspsbt(psbt=signed_psbt_obj.to_base64(), finalize=False)
@@ -185,11 +184,11 @@ class PSBTTest(BitcoinTestFramework):
         psbtx1 = wallet.walletcreatefundedpsbt([], {target_address: 0.1}, 0, {'fee_rate': 1, 'maxconf': 0})['psbt']
 
         # Make sure we only had the one input
-        tx1_inputs = self.nodes[0].decodepsbt(psbtx1)['tx']['vin']
+        tx1_inputs = self.nodes[0].decodepsbt(psbtx1)['inputs']
         assert_equal(len(tx1_inputs), 1)
 
         utxo1 = tx1_inputs[0]
-        assert_equal(unconfirmed_txid, utxo1['txid'])
+        assert_equal(unconfirmed_txid, utxo1['previous_txid'])
 
         signed_tx1 = wallet.walletprocesspsbt(psbtx1)
         txid1 = self.nodes[0].sendrawtransaction(signed_tx1['hex'])
@@ -198,23 +197,23 @@ class PSBTTest(BitcoinTestFramework):
         assert txid1 in mempool
 
         self.log.info("Fail to craft a new PSBT that sends more funds with add_inputs = False")
-        assert_raises_rpc_error(-4, "The preselected coins total amount does not cover the transaction target. Please allow other inputs to be automatically selected or include more coins manually", wallet.walletcreatefundedpsbt, [{'txid': utxo1['txid'], 'vout': utxo1['vout']}], {target_address: 1}, 0, {'add_inputs': False})
+        assert_raises_rpc_error(-4, "The preselected coins total amount does not cover the transaction target. Please allow other inputs to be automatically selected or include more coins manually", wallet.walletcreatefundedpsbt, [{'txid': utxo1['previous_txid'], 'vout': utxo1['previous_vout']}], {target_address: 1}, 0, {'add_inputs': False})
 
         self.log.info("Fail to craft a new PSBT with minconf above highest one")
-        assert_raises_rpc_error(-4, "Insufficient funds", wallet.walletcreatefundedpsbt, [{'txid': utxo1['txid'], 'vout': utxo1['vout']}], {target_address: 1}, 0, {'add_inputs': True, 'minconf': 3, 'fee_rate': 10})
+        assert_raises_rpc_error(-4, "Insufficient funds", wallet.walletcreatefundedpsbt, [{'txid': utxo1['previous_txid'], 'vout': utxo1['previous_vout']}], {target_address: 1}, 0, {'add_inputs': True, 'minconf': 3, 'fee_rate': 10})
 
         self.log.info("Fail to broadcast a new PSBT with maxconf 0 due to BIP125 rules to verify it actually chose unconfirmed outputs")
-        psbt_invalid = wallet.walletcreatefundedpsbt([{'txid': utxo1['txid'], 'vout': utxo1['vout']}], {target_address: 1}, 0, {'add_inputs': True, 'maxconf': 0, 'fee_rate': 10})['psbt']
+        psbt_invalid = wallet.walletcreatefundedpsbt([{'txid': utxo1['previous_txid'], 'vout': utxo1['previous_vout']}], {target_address: 1}, 0, {'add_inputs': True, 'maxconf': 0, 'fee_rate': 10})['psbt']
         signed_invalid = wallet.walletprocesspsbt(psbt_invalid)
         assert_raises_rpc_error(-26, "bad-txns-spends-conflicting-tx", self.nodes[0].sendrawtransaction, signed_invalid['hex'])
 
         self.log.info("Craft a replacement adding inputs with highest confs possible")
-        psbtx2 = wallet.walletcreatefundedpsbt([{'txid': utxo1['txid'], 'vout': utxo1['vout']}], {target_address: 1}, 0, {'add_inputs': True, 'minconf': 2, 'fee_rate': 10})['psbt']
-        tx2_inputs = self.nodes[0].decodepsbt(psbtx2)['tx']['vin']
+        psbtx2 = wallet.walletcreatefundedpsbt([{'txid': utxo1['previous_txid'], 'vout': utxo1['previous_vout']}], {target_address: 1}, 0, {'add_inputs': True, 'minconf': 2, 'fee_rate': 10})['psbt']
+        tx2_inputs = self.nodes[0].decodepsbt(psbtx2)['inputs']
         assert_greater_than_or_equal(len(tx2_inputs), 2)
         for vin in tx2_inputs:
-            if vin['txid'] != unconfirmed_txid:
-                assert_greater_than_or_equal(self.nodes[0].gettxout(vin['txid'], vin['vout'])['confirmations'], 2)
+            if vin['previous_txid'] != unconfirmed_txid:
+                assert_greater_than_or_equal(self.nodes[0].gettxout(vin['previous_txid'], vin['previous_vout'])['confirmations'], 2)
 
         signed_tx2 = wallet.walletprocesspsbt(psbtx2)
         txid2 = self.nodes[0].sendrawtransaction(signed_tx2['hex'])
@@ -387,7 +386,7 @@ class PSBTTest(BitcoinTestFramework):
         # The decodepsbt RPC is stateless and independent of any settings, we can always just call it on the first node
         decoded_psbt = self.nodes[0].decodepsbt(psbtx["psbt"])
         changepos = psbtx["changepos"]
-        assert_equal(decoded_psbt["tx"]["vout"][changepos]["scriptPubKey"]["type"], expected_type)
+        assert_equal(decoded_psbt["outputs"][changepos]["script"]["type"], expected_type)
 
     def test_psbt_named_parameter_handling(self):
         """Test that PSBT Base64 parameters with '=' padding are handled correctly in -named mode"""
@@ -429,17 +428,45 @@ class PSBTTest(BitcoinTestFramework):
     def test_psbt_roundtrip(self):
         self.log.info("Test that PSBTs roundtrip when RPC does nothing")
         utxo = self.nodes[0].listunspent()[0]
-        psbt = self.nodes[0].walletcreatefundedpsbt(inputs=[utxo], outputs=[{self.nodes[0].getnewaddress(): utxo["amount"] / 2}])["psbt"]
-
-        rt_psbts = [
-            self.nodes[0].combinepsbt([psbt, psbt]),
-            self.nodes[0].finalizepsbt(psbt)["psbt"],
-            self.nodes[0].utxoupdatepsbt(psbt),
-            self.nodes[0].descriptorprocesspsbt(psbt, [])["psbt"],
-            self.nodes[0].walletprocesspsbt(psbt, sign=False)["psbt"],
-        ]
-        for p in rt_psbts:
-            assert_equal(psbt, p)
+        for ver in [0, 2]:
+            psbt = self.nodes[0].walletcreatefundedpsbt(inputs=[utxo], outputs=[{self.nodes[0].getnewaddress(): utxo["amount"] / 2}], psbt_version=ver)["psbt"]
+
+            rt_psbts = [
+                self.nodes[0].combinepsbt([psbt, psbt]),
+                self.nodes[0].finalizepsbt(psbt)["psbt"],
+                self.nodes[0].utxoupdatepsbt(psbt),
+                self.nodes[0].descriptorprocesspsbt(psbt, [])["psbt"],
+                self.nodes[0].walletprocesspsbt(psbt, sign=False)["psbt"],
+            ]
+            for p in rt_psbts:
+                assert_equal(psbt, p)
+
+    def test_psbt_version(self):
+        tobump = self.nodes[0].sendtoaddress(self.nodes[0].getnewaddress(), 1)
+        utxo = self.nodes[0].listunspent()[0]
+        outputs = [{self.nodes[0].getnewaddress(): utxo["amount"] / 2}]
+        rawtx = self.nodes[0].createrawtransaction(inputs=[utxo], outputs=outputs)
+        for ver in [0, 2]:
+            psbt = self.nodes[0].createpsbt(inputs=[utxo], outputs=outputs, psbt_version=ver)
+            dec = self.nodes[0].decodepsbt(psbt)
+            assert_equal(ver, dec["psbt_version"])
+
+            psbt = self.nodes[0].walletcreatefundedpsbt(inputs=[utxo], outputs=outputs, psbt_version=ver)
+            dec = self.nodes[0].decodepsbt(psbt["psbt"])
+            assert_equal(ver, dec["psbt_version"])
+
+            psbt = self.nodes[0].converttopsbt(hexstring=rawtx, psbt_version=ver)
+            dec = self.nodes[0].decodepsbt(psbt)
+            assert_equal(ver, dec["psbt_version"])
+
+            psbt = self.nodes[0].psbtbumpfee(txid=tobump, psbt_version=ver)
+            dec = self.nodes[0].decodepsbt(psbt["psbt"])
+            assert_equal(ver, dec["psbt_version"])
+
+        assert_raises_rpc_error(-8, "The PSBT version can only be 2 or 0", self.nodes[0].createpsbt, inputs=[utxo], outputs=outputs, psbt_version=1)
+        assert_raises_rpc_error(-8, "The PSBT version can only be 2 or 0", self.nodes[0].walletcreatefundedpsbt, inputs=[utxo], outputs=outputs, psbt_version=1)
+        assert_raises_rpc_error(-8, "The PSBT version can only be 2 or 0", self.nodes[0].converttopsbt, hexstring=rawtx, psbt_version=1)
+        assert_raises_rpc_error(-8, "The PSBT version can only be 2 or 0", self.nodes[0].psbtbumpfee, txid=tobump, psbt_version=1)
 
     def run_test(self):
         # Create and fund a raw tx for sending 10 BTC
@@ -481,7 +508,9 @@ class PSBTTest(BitcoinTestFramework):
 
         max_tx_weight_sufficient = 1000 # 1k vbytes is enough
         psbt = self.nodes[0].walletcreatefundedpsbt(outputs=dest_arg,locktime=0, options={"max_tx_weight": max_tx_weight_sufficient})["psbt"]
-        weight = self.nodes[0].decodepsbt(psbt)["tx"]["weight"]
+        psbt = self.nodes[0].walletprocesspsbt(psbt)["psbt"]
+        final_tx = self.nodes[0].finalizepsbt(psbt)["hex"]
+        weight = self.nodes[0].decoderawtransaction(final_tx)["weight"]
         # ensure the transaction's weight is below the specified max_tx_weight.
         assert_greater_than_or_equal(max_tx_weight_sufficient, weight)
 
@@ -492,7 +521,7 @@ class PSBTTest(BitcoinTestFramework):
                                 self.nodes[0].walletcreatefundedpsbt, [{"txid": utxo1['txid'], "vout": utxo1['vout']}], {self.nodes[2].getnewaddress():90})
 
         psbtx1 = self.nodes[0].walletcreatefundedpsbt([{"txid": utxo1['txid'], "vout": utxo1['vout']}], {self.nodes[2].getnewaddress():90}, 0, {"add_inputs": True})['psbt']
-        assert_equal(len(self.nodes[0].decodepsbt(psbtx1)['tx']['vin']), 2)
+        assert_equal(len(self.nodes[0].decodepsbt(psbtx1)['inputs']), 2)
 
         # Inputs argument can be null
         self.nodes[0].walletcreatefundedpsbt(None, {self.nodes[2].getnewaddress():10})
@@ -735,12 +764,14 @@ class PSBTTest(BitcoinTestFramework):
         # Update psbts, should only have data for one input and not the other
         psbt1 = self.nodes[1].walletprocesspsbt(psbt_orig, False, "ALL")['psbt']
         psbt1_decoded = self.nodes[0].decodepsbt(psbt1)
-        assert psbt1_decoded['inputs'][0] and not psbt1_decoded['inputs'][1]
+        assert len(psbt1_decoded['inputs'][0].keys()) > 3
+        assert len(psbt1_decoded['inputs'][1].keys()) == 3
         # Check that BIP32 path was added
         assert "bip32_derivs" in psbt1_decoded['inputs'][0]
         psbt2 = self.nodes[2].walletprocesspsbt(psbt_orig, False, "ALL", False)['psbt']
         psbt2_decoded = self.nodes[0].decodepsbt(psbt2)
-        assert not psbt2_decoded['inputs'][0] and psbt2_decoded['inputs'][1]
+        assert len(psbt2_decoded['inputs'][0].keys()) == 3
+        assert len(psbt2_decoded['inputs'][1].keys()) > 3
         # Check that BIP32 paths were not added
         assert "bip32_derivs" not in psbt2_decoded['inputs'][1]
 
@@ -762,33 +793,33 @@ class PSBTTest(BitcoinTestFramework):
         unspent = self.nodes[0].listunspent()[0]
         psbtx_info = self.nodes[0].walletcreatefundedpsbt([{"txid":unspent["txid"], "vout":unspent["vout"]}], [{self.nodes[2].getnewaddress():unspent["amount"]+1}], block_height+2, {"replaceable": False, "add_inputs": True}, False)
         decoded_psbt = self.nodes[0].decodepsbt(psbtx_info["psbt"])
-        for tx_in, psbt_in in zip(decoded_psbt["tx"]["vin"], decoded_psbt["inputs"]):
-            assert_greater_than(tx_in["sequence"], MAX_BIP125_RBF_SEQUENCE)
+        for psbt_in in decoded_psbt["inputs"]:
+            assert_greater_than(psbt_in["sequence"], MAX_BIP125_RBF_SEQUENCE)
             assert "bip32_derivs" not in psbt_in
-        assert_equal(decoded_psbt["tx"]["locktime"], block_height+2)
+        assert_equal(decoded_psbt["fallback_locktime"], block_height+2)
 
         # Same construction with only locktime set and RBF explicitly enabled
         psbtx_info = self.nodes[0].walletcreatefundedpsbt([{"txid":unspent["txid"], "vout":unspent["vout"]}], [{self.nodes[2].getnewaddress():unspent["amount"]+1}], block_height, {"replaceable": True, "add_inputs": True}, True)
         decoded_psbt = self.nodes[0].decodepsbt(psbtx_info["psbt"])
-        for tx_in, psbt_in in zip(decoded_psbt["tx"]["vin"], decoded_psbt["inputs"]):
-            assert_equal(tx_in["sequence"], MAX_BIP125_RBF_SEQUENCE)
+        for psbt_in in decoded_psbt["inputs"]:
+            assert_equal(psbt_in["sequence"], MAX_BIP125_RBF_SEQUENCE)
             assert "bip32_derivs" in psbt_in
-        assert_equal(decoded_psbt["tx"]["locktime"], block_height)
+        assert_equal(decoded_psbt["fallback_locktime"], block_height)
 
         # Same construction without optional arguments
         psbtx_info = self.nodes[0].walletcreatefundedpsbt([], [{self.nodes[2].getnewaddress():unspent["amount"]+1}])
         decoded_psbt = self.nodes[0].decodepsbt(psbtx_info["psbt"])
-        for tx_in, psbt_in in zip(decoded_psbt["tx"]["vin"], decoded_psbt["inputs"]):
-            assert_equal(tx_in["sequence"], MAX_BIP125_RBF_SEQUENCE)
+        for psbt_in in decoded_psbt["inputs"]:
+            assert_equal(psbt_in["sequence"], MAX_BIP125_RBF_SEQUENCE)
             assert "bip32_derivs" in psbt_in
-        assert_equal(decoded_psbt["tx"]["locktime"], 0)
+        assert_equal(decoded_psbt["fallback_locktime"], 0)
 
         # Same construction without optional arguments, for a node with -walletrbf=0
         unspent1 = self.nodes[1].listunspent()[0]
         psbtx_info = self.nodes[1].walletcreatefundedpsbt([{"txid":unspent1["txid"], "vout":unspent1["vout"]}], [{self.nodes[2].getnewaddress():unspent1["amount"]+1}], block_height, {"add_inputs": True})
         decoded_psbt = self.nodes[1].decodepsbt(psbtx_info["psbt"])
-        for tx_in, psbt_in in zip(decoded_psbt["tx"]["vin"], decoded_psbt["inputs"]):
-            assert_greater_than(tx_in["sequence"], MAX_BIP125_RBF_SEQUENCE)
+        for psbt_in in decoded_psbt["inputs"]:
+            assert_greater_than(psbt_in["sequence"], MAX_BIP125_RBF_SEQUENCE)
             assert "bip32_derivs" in psbt_in
 
         # Make sure change address wallet does not have P2SH innerscript access to results in success
@@ -869,7 +900,7 @@ class PSBTTest(BitcoinTestFramework):
 
         # Creator Tests
         for creator in creators:
-            created_tx = self.nodes[0].createpsbt(inputs=creator['inputs'], outputs=creator['outputs'], replaceable=False)
+            created_tx = self.nodes[0].createpsbt(inputs=creator['inputs'], outputs=creator['outputs'], replaceable=False, psbt_version=creator['version'])
             assert_equal(created_tx, creator['result'])
 
         # Signer tests
@@ -923,46 +954,55 @@ class PSBTTest(BitcoinTestFramework):
         utxo1, utxo2, utxo3 = self.create_outpoints(self.nodes[1], outputs=[{addr1: 11}, {addr2: 11}, {addr3: 11}])
         self.sync_all()
 
+        psbt_v2_required_keys = ["previous_txid", "previous_vout", "sequence"]
+
         def test_psbt_input_keys(psbt_input, keys):
             """Check that the psbt input has only the expected keys."""
+            keys.extend(["previous_txid", "previous_vout", "sequence"])
             assert_equal(set(keys), set(psbt_input.keys()))
 
         # Create a PSBT. None of the inputs are filled initially
         psbt = self.nodes[1].createpsbt([utxo1, utxo2, utxo3], {self.nodes[0].getnewaddress():32.999})
         decoded = self.nodes[1].decodepsbt(psbt)
-        test_psbt_input_keys(decoded['inputs'][0], [])
-        test_psbt_input_keys(decoded['inputs'][1], [])
-        test_psbt_input_keys(decoded['inputs'][2], [])
+        test_psbt_input_keys(decoded['inputs'][0], psbt_v2_required_keys)
+        test_psbt_input_keys(decoded['inputs'][1], psbt_v2_required_keys)
+        test_psbt_input_keys(decoded['inputs'][2], psbt_v2_required_keys)
 
         # Update a PSBT with UTXOs from the node
         # Bech32 inputs should be filled with witness UTXO. Other inputs should not be filled because they are non-witness
         updated = self.nodes[1].utxoupdatepsbt(psbt)
         decoded = self.nodes[1].decodepsbt(updated)
-        test_psbt_input_keys(decoded['inputs'][0], ['witness_utxo', 'non_witness_utxo'])
-        test_psbt_input_keys(decoded['inputs'][1], ['non_witness_utxo'])
-        test_psbt_input_keys(decoded['inputs'][2], ['non_witness_utxo'])
+        test_psbt_input_keys(decoded['inputs'][0], psbt_v2_required_keys + ['witness_utxo', 'non_witness_utxo'])
+        test_psbt_input_keys(decoded['inputs'][1], psbt_v2_required_keys + ['non_witness_utxo'])
+        test_psbt_input_keys(decoded['inputs'][2], psbt_v2_required_keys + ['non_witness_utxo'])
 
         # Try again, now while providing descriptors, making P2SH-segwit work, and causing bip32_derivs and redeem_script to be filled in
         descs = [self.nodes[1].getaddressinfo(addr)['desc'] for addr in [addr1,addr2,addr3]]
         updated = self.nodes[1].utxoupdatepsbt(psbt=psbt, descriptors=descs)
         decoded = self.nodes[1].decodepsbt(updated)
-        test_psbt_input_keys(decoded['inputs'][0], ['witness_utxo', 'non_witness_utxo', 'bip32_derivs'])
-        test_psbt_input_keys(decoded['inputs'][1], ['non_witness_utxo', 'bip32_derivs'])
-        test_psbt_input_keys(decoded['inputs'][2], ['non_witness_utxo','witness_utxo', 'bip32_derivs', 'redeem_script'])
+        test_psbt_input_keys(decoded['inputs'][0], psbt_v2_required_keys + ['witness_utxo', 'non_witness_utxo', 'bip32_derivs'])
+        test_psbt_input_keys(decoded['inputs'][1], psbt_v2_required_keys + ['non_witness_utxo', 'bip32_derivs'])
+        test_psbt_input_keys(decoded['inputs'][2], psbt_v2_required_keys + ['non_witness_utxo', 'witness_utxo', 'bip32_derivs', 'redeem_script'])
+
+        # Cannot join PSBTv2s
+        psbt1 = self.nodes[1].createpsbt(inputs=[utxo1], outputs={self.nodes[0].getnewaddress():Decimal('10.999')}, psbt_version=0)
+        psbt2 = self.nodes[1].createpsbt(inputs=[utxo1], outputs={self.nodes[0].getnewaddress():Decimal('10.999')}, psbt_version=2)
+        assert_raises_rpc_error(-8, "joinpsbts only operates on version 0 PSBTs", self.nodes[1].joinpsbts, [psbt1, psbt2])
 
         # Two PSBTs with a common input should not be joinable
-        psbt1 = self.nodes[1].createpsbt([utxo1], {self.nodes[0].getnewaddress():Decimal('10.999')})
-        assert_raises_rpc_error(-8, "exists in multiple PSBTs", self.nodes[1].joinpsbts, [psbt1, updated])
+        psbt2 = self.nodes[1].createpsbt([utxo1], {self.nodes[0].getnewaddress():Decimal('10.999')}, psbt_version=0)
+        assert_raises_rpc_error(-8, "exists in multiple PSBTs", self.nodes[1].joinpsbts, [psbt1, psbt2])
 
         # Join two distinct PSBTs
+        psbt1 = self.nodes[1].createpsbt(inputs=[utxo1, utxo2, utxo3], outputs={self.nodes[0].getnewaddress():32.999}, psbt_version=0)
         addr4 = self.nodes[1].getnewaddress("", "p2sh-segwit")
         utxo4 = self.create_outpoints(self.nodes[0], outputs=[{addr4: 5}])[0]
         self.generate(self.nodes[0], 6)
-        psbt2 = self.nodes[1].createpsbt([utxo4], {self.nodes[0].getnewaddress():Decimal('4.999')})
+        psbt2 = self.nodes[1].createpsbt([utxo4], {self.nodes[0].getnewaddress():Decimal('4.999')}, psbt_version=0)
         psbt2 = self.nodes[1].walletprocesspsbt(psbt2)['psbt']
         psbt2_decoded = self.nodes[0].decodepsbt(psbt2)
         assert "final_scriptwitness" in psbt2_decoded['inputs'][0] and "final_scriptSig" in psbt2_decoded['inputs'][0]
-        joined = self.nodes[0].joinpsbts([psbt, psbt2])
+        joined = self.nodes[0].joinpsbts([psbt1, psbt2])
         joined_decoded = self.nodes[0].decodepsbt(joined)
         assert_equal(len(joined_decoded['inputs']), 4)
         assert_equal(len(joined_decoded['outputs']), 2)
@@ -973,7 +1013,7 @@ class PSBTTest(BitcoinTestFramework):
         # 10 attempts should be enough to get a shuffled join
         shuffled = False
         for _ in range(10):
-            shuffled_joined = self.nodes[0].joinpsbts([psbt, psbt2])
+            shuffled_joined = self.nodes[0].joinpsbts([psbt1, psbt2])
             shuffled |= joined != shuffled_joined
             if shuffled:
                 break
@@ -1071,11 +1111,9 @@ class PSBTTest(BitcoinTestFramework):
         final = signed['hex']
 
         dec = self.nodes[0].decodepsbt(signed["psbt"])
-        for i, txin in enumerate(dec["tx"]["vin"]):
-            if txin["txid"] == ext_utxo["txid"] and txin["vout"] == ext_utxo["vout"]:
-                input_idx = i
+        for psbt_in in dec["inputs"]:
+            if psbt_in["previous_txid"] == ext_utxo["txid"] and psbt_in["previous_vout"] == ext_utxo["vout"]:
                 break
-        psbt_in = dec["inputs"][input_idx]
         scriptsig_hex = psbt_in["final_scriptSig"]["hex"] if "final_scriptSig" in psbt_in else ""
         witness_stack_hex = psbt_in["final_scriptwitness"] if "final_scriptwitness" in psbt_in else None
         input_weight = calculate_input_weight(scriptsig_hex, witness_stack_hex)
@@ -1195,7 +1233,7 @@ class PSBTTest(BitcoinTestFramework):
         assert_equal(comb_psbt, psbt)
 
         self.log.info("Test walletprocesspsbt raises if an invalid sighashtype is passed")
-        assert_raises_rpc_error(-8, "'all' is not a valid sighash parameter.", self.nodes[0].walletprocesspsbt, psbt, sighashtype="all")
+        assert_raises_rpc_error(-8, "'all' is not a valid sighash parameter.", self.nodes[0].walletprocesspsbt, psbt=psbt, sighashtype="all")
 
         self.log.info("Test decoding PSBT with per-input preimage types")
         # note that the decodepsbt RPC doesn't check whether preimages and hashes match
@@ -1303,13 +1341,14 @@ class PSBTTest(BitcoinTestFramework):
         self.nodes[2].sendrawtransaction(processed_psbt['hex'])
 
         self.log.info("Test descriptorprocesspsbt raises if an invalid sighashtype is passed")
-        assert_raises_rpc_error(-8, "'all' is not a valid sighash parameter.", self.nodes[2].descriptorprocesspsbt, psbt, [descriptor], sighashtype="all")
+        assert_raises_rpc_error(-8, "'all' is not a valid sighash parameter.", self.nodes[2].descriptorprocesspsbt, psbt=psbt, descriptors=[descriptor], sighashtype="all")
 
         if not self.options.usecli:
             self.test_sighash_mismatch()
         self.test_sighash_adding()
         self.test_psbt_named_parameter_handling()
         self.test_psbt_roundtrip()
+        self.test_psbt_version()
 
 if __name__ == '__main__':
     PSBTTest(__file__).main()
diff --git a/test/functional/wallet_bumpfee.py b/test/functional/wallet_bumpfee.py
index 80735e01..961f1a14 100755
--- a/test/functional/wallet_bumpfee.py
+++ b/test/functional/wallet_bumpfee.py
@@ -608,14 +608,14 @@ def test_watchonly_psbt(self, peer_node, rbf_node, dest_address):
             {"fee_rate": 1, "add_inputs": False}, True)['psbt']
     psbt_signed = signer.walletprocesspsbt(psbt=psbt, sign=True, sighashtype="ALL", bip32derivs=True)
     original_txid = watcher.sendrawtransaction(psbt_signed["hex"])
-    assert_equal(len(watcher.decodepsbt(psbt)["tx"]["vin"]), 1)
+    assert_equal(len(watcher.decodepsbt(psbt)["inputs"]), 1)
 
     # bumpfee can't be used on watchonly wallets
     assert_raises_rpc_error(-4, "bumpfee is not available with wallets that have private keys disabled. Use psbtbumpfee instead.", watcher.bumpfee, original_txid)
 
     # Bump fee, obnoxiously high to add additional watchonly input
     bumped_psbt = watcher.psbtbumpfee(original_txid, fee_rate=HIGH)
-    assert_greater_than(len(watcher.decodepsbt(bumped_psbt['psbt'])["tx"]["vin"]), 1)
+    assert_greater_than(len(watcher.decodepsbt(bumped_psbt['psbt'])["inputs"]), 1)
     assert "txid" not in bumped_psbt
     assert_equal(bumped_psbt["origfee"], -watcher.gettransaction(original_txid)["fee"])
     assert not watcher.finalizepsbt(bumped_psbt["psbt"])["complete"]
diff --git a/test/functional/wallet_fundrawtransaction.py b/test/functional/wallet_fundrawtransaction.py
index a00e7e68..02227029 100755
--- a/test/functional/wallet_fundrawtransaction.py
+++ b/test/functional/wallet_fundrawtransaction.py
@@ -1176,10 +1176,10 @@ class RawTransactionsTest(BitcoinTestFramework):
         tx = wallet.send(outputs=[{addr1: 8}], **options)
         assert tx["complete"]
         # Check that only the preset inputs were added to the tx
-        decoded_psbt_inputs = self.nodes[0].decodepsbt(tx["psbt"])['tx']['vin']
+        decoded_psbt_inputs = self.nodes[0].decodepsbt(tx["psbt"])["inputs"]
         assert_equal(len(decoded_psbt_inputs), 2)
         for input in decoded_psbt_inputs:
-            assert_equal(input["txid"], source_tx["txid"])
+            assert_equal(input["previous_txid"], source_tx["txid"])
 
         # Case (5), assert that inputs are added to the tx by explicitly setting add_inputs=true
         options = {"add_inputs": True, "add_to_wallet": True}
@@ -1218,10 +1218,10 @@ class RawTransactionsTest(BitcoinTestFramework):
         })
         psbt_tx = wallet.walletcreatefundedpsbt(outputs=[{addr1: 8}], inputs=inputs, **options)
         # Check that only the preset inputs were added to the tx
-        decoded_psbt_inputs = self.nodes[0].decodepsbt(psbt_tx["psbt"])['tx']['vin']
+        decoded_psbt_inputs = self.nodes[0].decodepsbt(psbt_tx["psbt"])["inputs"]
         assert_equal(len(decoded_psbt_inputs), 2)
         for input in decoded_psbt_inputs:
-            assert_equal(input["txid"], source_tx["txid"])
+            assert_equal(input["previous_txid"], source_tx["txid"])
 
         # Case (5), 'walletcreatefundedpsbt' command
         # Explicit add_inputs=true, no preset inputs
diff --git a/test/functional/wallet_multisig_descriptor_psbt.py b/test/functional/wallet_multisig_descriptor_psbt.py
index a3236a22..85051c34 100755
--- a/test/functional/wallet_multisig_descriptor_psbt.py
+++ b/test/functional/wallet_multisig_descriptor_psbt.py
@@ -36,13 +36,13 @@ class WalletMultisigDescriptorPSBTTest(BitcoinTestFramework):
     @staticmethod
     def _check_psbt(psbt, to, value, multisig):
         """Helper function for any of the N participants to check the psbt with decodepsbt and verify it is OK before signing."""
-        tx = multisig.decodepsbt(psbt)["tx"]
+        decoded = multisig.decodepsbt(psbt)
         amount = 0
-        for vout in tx["vout"]:
-            address = vout["scriptPubKey"]["address"]
+        for psbt_out in decoded["outputs"]:
+            address = psbt_out["script"]["address"]
             assert_equal(multisig.getaddressinfo(address)["ischange"], address != to)
             if address == to:
-                amount += vout["value"]
+                amount += psbt_out["amount"]
         assert_approx(amount, float(value), vspan=0.001)
 
     def participants_create_multisigs(self, xpubs):
diff --git a/test/functional/wallet_send.py b/test/functional/wallet_send.py
index 213c4756..ba986990 100755
--- a/test/functional/wallet_send.py
+++ b/test/functional/wallet_send.py
@@ -395,10 +395,10 @@ class WalletSendTest(BitcoinTestFramework):
         assert res["complete"]
         res = self.test_send(from_wallet=w0, to_wallet=w1, amount=1, add_to_wallet=False, change_address=change_address, change_position=0)
         assert res["complete"]
-        assert_equal(self.nodes[0].decodepsbt(res["psbt"])["tx"]["vout"][0]["scriptPubKey"]["address"], change_address)
+        assert_equal(self.nodes[0].decodepsbt(res["psbt"])["outputs"][0]["script"]["address"], change_address)
         res = self.test_send(from_wallet=w0, to_wallet=w1, amount=1, add_to_wallet=False, change_type="legacy", change_position=0)
         assert res["complete"]
-        change_address = self.nodes[0].decodepsbt(res["psbt"])["tx"]["vout"][0]["scriptPubKey"]["address"]
+        change_address = self.nodes[0].decodepsbt(res["psbt"])["outputs"][0]["script"]["address"]
         assert change_address[0] in ("m", "n")
 
         self.log.info("Set lock time...")
@@ -498,11 +498,9 @@ class WalletSendTest(BitcoinTestFramework):
         assert signed["complete"]
 
         dec = self.nodes[0].decodepsbt(signed["psbt"])
-        for i, txin in enumerate(dec["tx"]["vin"]):
-            if txin["txid"] == ext_utxo["txid"] and txin["vout"] == ext_utxo["vout"]:
-                input_idx = i
+        for psbt_in in dec["inputs"]:
+            if psbt_in["previous_txid"] == ext_utxo["txid"] and psbt_in["previous_vout"] == ext_utxo["vout"]:
                 break
-        psbt_in = dec["inputs"][input_idx]
         scriptsig_hex = psbt_in["final_scriptSig"]["hex"] if "final_scriptSig" in psbt_in else ""
         witness_stack_hex = psbt_in["final_scriptwitness"] if "final_scriptwitness" in psbt_in else None
         input_weight = calculate_input_weight(scriptsig_hex, witness_stack_hex)
diff --git a/test/functional/wallet_sendall.py b/test/functional/wallet_sendall.py
index 1977a1e2..0524b5c8 100755
--- a/test/functional/wallet_sendall.py
+++ b/test/functional/wallet_sendall.py
@@ -308,9 +308,9 @@ class SendallTest(BitcoinTestFramework):
         decoded = self.nodes[0].decodepsbt(psbt)
         assert_equal(len(decoded["inputs"]), 1)
         assert_equal(len(decoded["outputs"]), 1)
-        assert_equal(decoded["tx"]["vin"][0]["txid"], utxo["txid"])
-        assert_equal(decoded["tx"]["vin"][0]["vout"], utxo["vout"])
-        assert_equal(decoded["tx"]["vout"][0]["scriptPubKey"]["address"], self.remainder_target)
+        assert_equal(decoded["inputs"][0]["previous_txid"], utxo["txid"])
+        assert_equal(decoded["inputs"][0]["previous_vout"], utxo["vout"])
+        assert_equal(decoded["outputs"][0]["script"]["address"], self.remainder_target)
 
     @cleanup
     def sendall_with_minconf(self):
diff --git a/test/functional/wallet_v3_txs.py b/test/functional/wallet_v3_txs.py
index 446dc086..18fa0d54 100755
--- a/test/functional/wallet_v3_txs.py
+++ b/test/functional/wallet_v3_txs.py
@@ -448,7 +448,7 @@ class WalletV3Test(BitcoinTestFramework):
 
         outputs = {self.alice.getnewaddress() : 10}
         psbt = self.charlie.createpsbt(inputs=[], outputs=outputs, version=3)
-        assert_equal(self.charlie.decodepsbt(psbt)["tx"]["version"], 3)
+        assert_equal(self.charlie.decodepsbt(psbt)["tx_version"], 3)
 
     @cleanup
     def send_v3(self):
@@ -526,7 +526,7 @@ class WalletV3Test(BitcoinTestFramework):
 
         outputs = {self.alice.getnewaddress() : 10}
         psbt = self.charlie.walletcreatefundedpsbt(inputs=[], outputs=outputs, version=3)["psbt"]
-        assert_equal(self.charlie.decodepsbt(psbt)["tx"]["version"], 3)
+        assert_equal(self.charlie.decodepsbt(psbt)["tx_version"], 3)
 
     @cleanup
     def sendall_truc_weight_limit(self):