How to add a dedicated account for fee paying ?

[kaiyes]

Hi, I've been trying in vein to add a fee payer account like we can for sending sols.

const swapTransactionBuf = Buffer.from(swapResult.swapTransaction, 'base64')
var transaction = VersionedTransaction.deserialize(swapTransactionBuf)

// Set fee payer
transaction.feePayer = feePayerkeypair.publicKey // Ensure the transaction's fee payer is set

transaction.recentBlockhash = (
await connection.getRecentBlockhash()
).blockhash

// Sign the transaction with both the wallet and the fee payer
transaction.sign([feePayer.keypair, accountKeypayer ]) // Sign the transaction with both the user's wallet and the fee payer

I always get the error "Cannot sign with non signer key"

[kaiyes]

This issue has the exact same problem as mine, but no answers there either
https://solana.stackexchange.com/questions/7432/setting-feepayer-of-versionedtransaction

[winter2009]

is there any udpate?

[distbit0]

I've also got the exact same issue

[sofix91]

@kaiyes

You are dealing with a Versioned Transaction. The way that you are doing right now is for Legacy transactions.

So you need to deserialize the transaction, fetch Address Lookup Tables, decompile the message, add your fee payer as one of the message signers, recompile the message fetch latest blockhash, sign with the main key, sign with the feepayer key, and send.

https://solana.com/fr/docs/advanced/versions