Steps to reproduce on regtest:

```
converttopsbt 02000000000101ab73dba46508bacdb49a988ddd74bc9d39c9cb7e057af060ca8c6b6861e28e3c0300000000feffffff02b828d0b20000000017a914d1954862afd728fbb055149002958e1d1b9e1f0b8700ca9a3b0000000017a91442170ccb3441cff1723af9afab6f2553103e1d578702473044022077380c6e16496d9905aef120694c329be51522847cb5d53fa74b94698c95678d02202d32c46e0e17420a83dee830fefda7d40529182f5d82be47c2b49a7b83214ab50121026d483d6628dcc3ef6e3ab9ed4937c452c263c7e0ac80eb4be97426d5da8f640500000000
```
or 
```
converttopsbt 02000000000101ab73dba46508bacdb49a988ddd74bc9d39c9cb7e057af060ca8c6b6861e28e3c0300000000feffffff02b828d0b20000000017a914d1954862afd728fbb055149002958e1d1b9e1f0b8700ca9a3b0000000017a91442170ccb3441cff1723af9afab6f2553103e1d578702473044022077380c6e16496d9905aef120694c329be51522847cb5d53fa74b94698c95678d02202d32c46e0e17420a83dee830fefda7d40529182f5d82be47c2b49a7b83214ab50121026d483d6628dcc3ef6e3ab9ed4937c452c263c7e0ac80eb4be97426d5da8f640500000000 false
```

Further reading: #13738
{
    const RPCHelpMan help{"converttopsbt",
                "\nConverts a network serialized transaction to a PSBT. This should be used only with createrawtransaction and fundrawtransaction\n"
                "createpsbt and walletcreatefundedpsbt should be used for new applications.\n",
                {
                    {"hexstring", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The hex string of a raw transaction"},
                    {"permitsigdata", RPCArg::Type::BOOL,  "false", "If true, any signatures in the input will be discarded and conversion.\n"
                            "                              will continue. If false, RPC will fail if any signatures are present."},
                    {"iswitness", RPCArg::Type::BOOL,  "depends on heuristic tests", "Whether the transaction hex is a serialized witness transaction.\n"
                            "                              If iswitness is not present, heuristic tests will be used in decoding. If true, only witness deserializaion\n"
                            "                              will be tried. If false, only non-witness deserialization will be tried. Only has an effect if\n"
                            "                              permitsigdata is true."},
                },
                RPCResult{
                            "  \"psbt\"        (string)  The resulting raw transaction (base64-encoded string)\n"
                },
                RPCExamples{
                            "\nCreate a transaction\n"
                            + HelpExampleCli("createrawtransaction", "\"[{\\\"txid\\\":\\\"myid\\\",\\\"vout\\\":0}]\" \"[{\\\"data\\\":\\\"00010203\\\"}]\"") +
                            "\nConvert the transaction to a PSBT\n"
                            + HelpExampleCli("converttopsbt", "\"rawtransaction\"")
                },
    };
    if (request.fHelp || !help.IsValidNumArgs(request.params.size())) {
        throw std::runtime_error(help.ToString());
    }
    RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VBOOL, UniValue::VBOOL}, true);
    
    CMutableTransaction tx;
    bool permitsigdata = request.params[1].isNull() ? false : request.params[1].get_bool();