so i'm runing this to prompt a transaction on nami wallet, sign and submit. the ideal scenario was to nami wallet submit transaction for herself but somehow that is not happening, so i tried to submit via blockfrost api.

the script that i paste on devtools console:

// Replace this with your transaction data
const cborEncodedTransaction =
  // Your CBOR encoded transaction data here

// Replace this with your API key from Blockfrost

async function signAndSubmitTransaction(cborEncodedTransaction) {
  try {
    // Check if Nami Wallet is available
    if (!window.cardano) {
      throw new Error("Nami Wallet is not available. Make sure you have the Nami Wallet extension installed.");

    // Sign the transaction using Nami Wallet
    const partialSign = true; // Set this to true to enable partial signing
    const transactionWitnessSet = await window.cardano.signTx(cborEncodedTransaction, partialSign);

    // Convert the transactionWitnessSet to a hex-encoded string
    const signedCborTransaction = transactionWitnessSet;
    console.log("Signed Transaction (hex-encoded):", signedCborTransaction);

    // Submit the transaction using Blockfrost API
    console.log("Submitting transaction to Blockfrost...");
    console.log("CBOR Encoded Transaction with Witness:", signedCborTransaction);

    const response = await fetch("https://cardano-mainnet.blockfrost.io/api/v0/tx/submit", {
      method: "POST",
      headers: {
        "Content-Type": "application/cbor",
        "Project_id": apiKey,
      body: signedCborTransaction,

    console.log("Blockfrost Response Status:", response.status);
    console.log("Blockfrost Response Data:", await response.json());

    if (!response.ok) {
      const errorData = await response.json();
      throw new Error(`Blockfrost API error: ${errorData.error}, ${errorData.message}`);

    console.log("Transaction submitted successfully.");
  } catch (error) {
    console.error("Error signing or submitting transaction:", error);
    throw error;

// Call the signAndSubmitTransaction function with the transaction data

the error that i get:

    "error": "Bad Request",
    "message": "\"transaction read error RawCborDecodeError [DecoderErrorDeserialiseFailure \\\"Byron Tx\\\" (DeserialiseFailure 0 \\\"expected list len\\\"),DecoderErrorDeserialiseFailure \\\"Shelley Tx\\\" (DeserialiseFailure 0 \\\"expected list len or indef\\\"),DecoderErrorDeserialiseFailure \\\"Shelley Tx\\\" (DeserialiseFailure 0 \\\"expected list len or indef\\\"),DecoderErrorDeserialiseFailure \\\"Shelley Tx\\\" (DeserialiseFailure 0 \\\"expected list len or indef\\\"),DecoderErrorDeserialiseFailure \\\"Shelley Tx\\\" (DeserialiseFailure 0 \\\"expected list len or indef\\\"),DecoderErrorDeserialiseFailure \\\"Shelley Tx\\\" (DeserialiseFailure 0 \\\"expected list len or indef\\\")]\"",
    "status_code": 400

the nami window pops up with the correct transaction for me to signed it, and after that the error happens.

1 Answer 1


Your variable signedCborTransaction is just key witnesses for inputs being spent in this transaction that belong to your wallet, specifically, it's CBOR of transaction_witness_set with only entries for 0th key as per this CDDL specification. You would need to add this witness to your original transaction (cborEncodedTransaction) and then submit it.

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