Unknown error / unknown output script type

[gomesalexandre]

Summary

gm!

While I was trying to debug some issue with BTC sends with signPSBT being broken for some addresses (i.e popup shows just fine, but after clicking confirm, signPSBT throws), I eventually ran out of luck re: -32603 unexpected error.

Digging deeper, while running Devtools in Phantom, I saw this error which wasn't exposed:
Transaction/output: unknown output script type, there is a chance that input is unspendable. Pass allowUnknownOutputs=true, if you sure which seems to come from scure-btc-signer
Wondering if we could bubble those errors up to consumers instead of "unexpected error" to help with future debugging?

And indeed, while running a breakpoint on the affected line of scure-btc-signer, script type was unknown.

Now, the really weird part here is

• this was only happening while testing witha specific account, bc1qsdeav5z8pt307euz742xla97gackhgpkz27dh5, but was not happening while testing with another, bc1qxzntwam7733myh5vryz5dptpqg79d0kn80clmt
• both accounts (addresses) are 0th account_index, both are zpubs (SegWit native), and obviously both are 0th address_index as that's the only one that Phantom ever uses (no next receive address with Phantom)
• Only the former (bc1...dh5) was failing while trying to send to any address, while the second could send to any (self-send, or outputs going to external addresses)
• after a send through Phantom, things eventually automagically got fixed, and I couldn't repro this at all i.e couldn't get to this error anymore not to unknown script in the affected line in scure-btc-signer while debugging Phantom extension.

This is what the psbt looked like for the affected Tx:

{
    "data": {
        "inputs": [
            {
                "unknownKeyVals": [],
                "nonWitnessUtxo": {
                    "type": "Buffer",
                    "data": [
                        2,
                        0,
                        0,
                        0,
                        0,
                        1,
                        1,
                        99,
                        244,
                        189,
                        225,
                        182,
                        162,
                        184,
                        136,
                        131,
                        135,
                        83,
                        164,
                        110,
                        255,
                        116,
                        143,
                        104,
                        69,
                        120,
                        197,
                        145,
                        96,
                        197,
                        244,
                        56,
                        115,
                        185,
                        157,
                        155,
                        18,
                        242,
                        255,
                        0,
                        0,
                        0,
                        0,
                        0,
                        255,
                        255,
                        255,
                        255,
                        3,
                        229,
                        41,
                        0,
                        0,
                        0,
                        0,
                        0,
                        0,
                        22,
                        0,
                        20,
                        149,
                        64,
                        248,
                        25,
                        104,
                        211,
                        1,
                        203,
                        77,
                        72,
                        122,
                        27,
                        209,
                        191,
                        77,
                        34,
                        9,
                        159,
                        180,
                        35,
                        55,
                        73,
                        0,
                        0,
                        0,
                        0,
                        0,
                        0,
                        22,
                        0,
                        20,
                        131,
                        115,
                        214,
                        80,
                        71,
                        10,
                        226,
                        255,
                        103,
                        130,
                        245,
                        84,
                        111,
                        244,
                        190,
                        71,
                        113,
                        107,
                        160,
                        54,
                        0,
                        0,
                        0,
                        0,
                        0,
                        0,
                        0,
                        0,
                        66,
                        106,
                        64,
                        61,
                        58,
                        69,
                        84,
                        72,
                        46,
                        69,
                        84,
                        72,
                        58,
                        48,
                        120,
                        55,
                        48,
                        49,
                        54,
                        101,
                        54,
                        98,
                        99,
                        51,
                        99,
                        52,
                        101,
                        53,
                        52,
                        57,
                        53,
                        51,
                        101,
                        55,
                        48,
                        99,
                        49,
                        53,
                        53,
                        50,
                        100,
                        51,
                        55,
                        102,
                        52,
                        101,
                        100,
                        97,
                        49,
                        55,
                        51,
                        98,
                        48,
                        54,
                        51,
                        58,
                        50,
                        52,
                        53,
                        57,
                        49,
                        53,
                        58,
                        115,
                        115,
                        58,
                        48,
                        2,
                        71,
                        48,
                        68,
                        2,
                        32,
                        8,
                        39,
                        151,
                        20,
                        116,
                        17,
                        5,
                        42,
                        83,
                        254,
                        121,
                        40,
                        190,
                        232,
                        71,
                        96,
                        226,
                        194,
                        188,
                        92,
                        212,
                        20,
                        22,
                        66,
                        189,
                        55,
                        121,
                        204,
                        192,
                        50,
                        3,
                        56,
                        2,
                        32,
                        24,
                        119,
                        37,
                        220,
                        235,
                        179,
                        197,
                        1,
                        149,
                        14,
                        125,
                        92,
                        49,
                        254,
                        88,
                        72,
                        166,
                        103,
                        201,
                        90,
                        164,
                        214,
                        103,
                        182,
                        176,
                        21,
                        4,
                        108,
                        39,
                        143,
                        193,
                        41,
                        1,
                        33,
                        3,
                        153,
                        146,
                        159,
                        150,
                        179,
                        189,
                        66,
                        81,
                        205,
                        111,
                        182,
                        161,
                        29,
                        127,
                        254,
                        129,
                        155,
                        106,
                        200,
                        168,
                        6,
                        188,
                        98,
                        175,
                        156,
                        94,
                        140,
                        55,
                        49,
                        151,
                        45,
                        128,
                        0,
                        0,
                        0,
                        0
                    ]
                }
            }
        ],
        "outputs": [
            {
                "unknownKeyVals": []
            },
            {
                "unknownKeyVals": []
            }
        ],
        "globalMap": {
            "unsignedTx": {}
        }
    }
}

And inputsToSign:

[
    {
        "address": "bc1qsdeav5z8pt307euz742xla97gackhgpkz27dh5",
        "signingIndexes": [
            0
        ],
        "sigHash": 1
    }
]

FYI, this is our internal data structure that we massage to conform to Phantom:

{
    "coin": "Bitcoin",
    "inputs": [
        {
            "addressNList": [
                2147483732,
                2147483648,
                2147483648,
                0,
                0
            ],
            "scriptType": "p2wpkh",
            "amount": "18743",
            "vout": 1,
            "txid": "447eceea134ee90f5f126f3ab462846daf1b263d468309420b4a1a8675603567",
            "hex": "redacted"
        }
    ],
    "outputs": [
        {
            "addressType": "spend",
            "amount": "1037",
            "address": "bc1qsdeav5z8pt307euz742xla97gackhgpkz27dh5"
        },
        {
            "addressType": "change",
            "amount": "15898",
            "addressNList": [
                2147483732,
                2147483648,
                2147483648,
                1,
                0
            ],
            "scriptType": "p2wpkh",
            "isChange": true
        }
    ]
}

Kind of a long shot here as we're more trying to understand the actual heuristics to repro and whether or not this is an internal Phantom issue, rather than the fix (fix in this case is to do a send through Phantom, though obviously more of a bandaid than anything else).

I noticed this comment from @adamdelphantom in the only similar issue I could find https://github.com/orgs/phantom/discussions/284#discussioncomment-10546475 - wondering if this could be a similar issue, and I assume the issue is Phantom having trouble with specific UTXO sets?

Example

No response

Steps to Reproduce

See above, not so much in terms of steps to reproduce as that's what we're actually trying to understand here!

Phantom Version

24.26.0

Is there an existing discussion for this?

• I have searched the existing discussions