I’m trying to create a child inscription in a Taproot transaction, but I’m running into the following error:

sendrawtransaction RPC error: {"code":-26,"message":"mandatory-script-verify-flag-failed (Invalid Schnorr signature)"}

I checked all the data, including transaction structure, signatures, TapRoot scripts, and more, but the error persists.

The input refers to the parent UTXO.

{
  "txid": "02cde20c6db772c9ddced410c52cb2bdcbf476016fa398cfa1ac5207f1ff462f",
  "vout": 0,
  "value": 546,
  "scriptPk": "5120932a0391d2ec13cb8f303ded9297ece089f739b3ced40bc98eebdd277fdb9c9d",
  "address": "tb1pjv4q8ywjasfuhres8hke99lvuzylwwdnem2qhjvwa0wjwl7mnjwsdqu3e0"
}

The output sends 546 Satoshis to the recipient address. The Taproot script for the child’s inscription includes:

Parent inscription data (InscriptionID). Child inscription metadata.

const childOrdinalStacks = (
  publicKey,
  bitcoin.opcodes.OP_CHECKSIG,
  bitcoin.opcodes.OP_FALSE,
  bitcoin.opcodes.OP_IF,
  Buffer.from("ord", "utf8"),
  1, 1,
  Buffer.from("text/plain;charset=utf-8", "utf8"),
  1, 2,
  pointerBuffer1,
  1, 3,
  Buffer.from(parentInscriptionId, "hex"),
  1, 5,
  cbor.encode(childMetadata),
  1, 7,
  Buffer.from("parcel.bitmap", "utf8"),
  bitcoin.opcodes.OP_0,
);

RAW TX Hash

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

I’m using Tweaksigner to sign the input.

const signer = tweakSigner(wallet);
psbt.signInput(0, signer);
psbt.signInput(1, wallet.keyPair);


export function tweakSigner(wallet: Wallet, opts: any = {}) {
  let privateKey: any = wallet.keyPair.privateKey;
  if (!privateKey) {
    throw new Error('Private key is required for tweaking signer!');
  }
  if (wallet.keyPair.publicKey(0) === 3) {
    privateKey = ecc.privateNegate(privateKey);
  }
  const tweakedPrivateKey = ecc.privateAdd(privateKey, tapTweakHash(wallet.internalPubkey, opts.tweakHash));
  if (!tweakedPrivateKey) {
    throw new Error('Invalid tweaked private key!');
  }
  return ECPair.fromPrivateKey(Buffer.from(tweakedPrivateKey), {
    network: wallet.network,
  });
}


function tapTweakHash(pubKey: Buffer, h: Buffer | undefined): Buffer {
  return bitcoin.crypto.taggedHash(
    "TapTweak",
    Buffer.concat(h ? (pubKey, h) : (pubKey))
  );
}