Why did this transaction fail?

[GrimLothar]

Hey! Sorry if this is not the place, Jacob told me to ask here about why a transaction would fail.

So I have this TX: https://solscan.io/tx/5NSH3J3zt5xSndALKWDxk7hsnEaMPHJrA21p193CnnzBpKjbE8iNkREm7VEH9N2pC83t8VAtH5YcSpBcjexfEycy?cluster=devnet (note that it is on Devnet)

That failed with custom program error: 6400

Why would that happen? And how can I prevent it? I'm not doing anything fancy... this is how I'm creating the transaction on my backend:

  // Parse addresses for transaction creation
    const recipientAddress = new PublicKey(MERCHANT_WALLET);
    const usdcMint = new PublicKey(USDC_MINT);
    const payerPubkey = new PublicKey(payerPublicKey);
    
    // Get token accounts
    const senderTokenAccount = await getAssociatedTokenAddress(
      usdcMint,
      payerPubkey,
      true // allow multisig accounts
    );
    
    const receiverTokenAccount = await getAssociatedTokenAddress(
      usdcMint,
      recipientAddress,
      true // allow multisig accounts
    );
    
    // Create transaction - amount needs to be adjusted for decimals (USDC has 6 decimals)
    const tokenAmount = Math.floor(amount * 1000000);
    
    const transaction = new Transaction().add(
      createTransferInstruction(
        senderTokenAccount,
        receiverTokenAccount,
        payerPubkey,
        BigInt(tokenAmount),
      )
    );
    
    // Get recent blockhash
    const { blockhash, lastValidBlockHeight } = await connection.getLatestBlockhash();
    transaction.recentBlockhash = blockhash;
    transaction.feePayer = payerPubkey;

Thank you!

[GrimLothar]

Looks like on this issue: #57 they are also getting the same 6400 error, and @Jac0xb mentioned the need to decode the bytes and would give an example. Any chance we can get that example? 🙏

[GrimLothar]

Ok, I had another look at the TX and the error itself is pretty clear in the Program Logs (sorry, was in a rush yesterday)

> Program log: Result (Failed): Some(8320000) >= Some(75131722)

The Assertion is checking whether the account has more than 75131722 lamports and it's failing... Now the question is WHY is it asserting for 75131722 lamports, when the tx fee is 0.00008 SOL, and priority fee is 0.000075 SOL. That's 155000 lamports. Why is lighthouse checking that the wallet has more than than 0.07513172 SOL???

Is this a lighthouse issue or a phantom issue?