Can't serialize or deserialize PSBT with no inputs

[andrewtoth]

const { Psbt } = require("bitcoinjs-lib");

const psbt = new Psbt();
psbt.addOutput({
  address: "1BM1sAcrfV6d4zPKytzziu4McLQDsFC2Qc",
  value: 100000n,
});
const base64 = psbt.toBase64();

console.log(base64); // cHNidP8BACwCAAAAAAGghgEAAAAAABl2qRRxekyQdFd6Ba+UJxwysknSmKItmIisAAAAAAAAAA==
Psbt.fromBase64(base64); // Throws

bitcoin-cli decodepsbt cHNidP8BACwCAAAAAAGghgEAAAAAABl2qRRxekyQdFd6Ba+UJxwysknSmKItmIisAAAAAAAAAA==
error code: -22
error message:
TX decode failed extra data after PSBT

bitcoin-cli createpsbt '[]' '[{"1BM1sAcrfV6d4zPKytzziu4McLQDsFC2Qc": 1000000}]'
cHNidP8BACwCAAAAAAEAoHJOGAkAABl2qRRxekyQdFd6Ba+UJxwysknSmKItmIisAAAAAAAA

bitcoin-cli decodepsbt cHNidP8BACwCAAAAAAEAoHJOGAkAABl2qRRxekyQdFd6Ba+UJxwysknSmKItmIisAAAAAAAA
{
  "tx": {
    "txid": "3b029267c47308599062841be4d19b8894c5521792091399a972516439f89f21",
    "hash": "3b029267c47308599062841be4d19b8894c5521792091399a972516439f89f21",
    "version": 2,
    "size": 44,
    "vsize": 44,
    "weight": 176,
    "locktime": 0,
    "vin": [
    ],
    "vout": [
      {
        "value": 100000.00000000,
        "n": 0,
        "scriptPubKey": {
          "asm": "OP_DUP OP_HASH160 717a4c9074577a05af94271c32b249d298a22d98 OP_EQUALVERIFY OP_CHECKSIG",
          "desc": "addr(1BM1sAcrfV6d4zPKytzziu4McLQDsFC2Qc)#ed77rxnh",
          "hex": "76a914717a4c9074577a05af94271c32b249d298a22d9888ac",
          "address": "1BM1sAcrfV6d4zPKytzziu4McLQDsFC2Qc",
          "type": "pubkeyhash"
        }
      }
    ]
  },
  "global_xpubs": [
  ],
  "psbt_version": 0,
  "proprietary": [
  ],
  "unknown": {
  },
  "inputs": [
  ],
  "outputs": [
    {
    }
  ],
  "fee": -100000.00000000
}

Psbt.fromBase64(
  "cHNidP8BACwCAAAAAAEAoHJOGAkAABl2qRRxekyQdFd6Ba+UJxwysknSmKItmIisAAAAAAAA"
); // Throws

[jasonandjay]

Maintainer triage: marking this as bug.

Could you share a minimal reproducible snippet and expected behavior per spec for zero-input PSBT serialization/deserialization? This will help us confirm whether this is a strict bug or a spec-boundary case.

[andrewtoth]

Could you share a minimal reproducible snippet and expected behavior per spec for zero-input PSBT serialization/deserialization?

Is the snippet and expected behavior above not sufficient?

The following PSBT is listed as valid in the spec's test vectors under Case: PSBT with 0 inputs.

cHNidP8BAEwCAAAAAALT3/UFAAAAABl2qRTQxZkDxbrChodg6Q/VIaRmWqdlIIisAOH1BQAAAAAXqRQ1RebjO4MsRwUPJNPuuTycA5SLx4ezLhMAAAAA

This one can be decoded by bitcoinjs-lib. It has 2 outputs though, and the one that fails above has 1 output.

[RyanBetz]

I ran a repo-mapping tool on this and it points to the parsing flow through fromBase64 → fromBuffer → PsbtBase.fromBuffer.

It’s not obvious from that path where zero-input assumptions are enforced, but it seems likely the issue is in how the transaction buffer is interpreted rather than the higher-level PSBT wrapper.