Confirming a processed transaction

Question

Using connection.confirmTransaction getting the following error:

confirmTransaction error: Cannot assign to read only property '_nextClientSubscriptionId' of object '#<Connection>'

const blockdetails = await connection.getLatestBlockhash();
tx.lastValidBlockHeight = blockdetails.lastValidBlockHeight;
tx.recentBlockhash = blockdetails.blockhash;
tx.feePayer = payer.publicKey;
const signedTx = await payer.signTransaction(tx);
const sendOptions: SendOptions = {
  maxRetries: 3,
  preflightCommitment: "processed",
  skipPreflight: true,
};
const txnSignature = await connection.sendRawTransaction(
  signedTx.serialize(),
  sendOptions
;

const confirmStrategy: BlockheightBasedTransactionConfirmationStrategy = {
  signature: txnSignature,
  blockhash: blockdetails.blockhash,
  lastValidBlockHeight: blockdetails.lastValidBlockHeight,
};

const conf = await connection.confirmTransaction(
  confirmStrategy,
  "processed"
);

Answer 1

This is almost certainly because you're using Vue, and:

• Your Connection object has undergone a reactive/readonly transformation
• Connection._nextClientSubscriptionId is now a readonly ref

Without seeing more of your code, my only suggestion is to figure out where this transformation is happening and either:

• stop it
• do it shallowly
• mark the Connection object as raw

Answer 2

Posting an updated answer as I ran into the same problem, but not using Vue.

In my case we are using Recoil for state management, which transforms objects to readonly. Those using Recoil for state management should add the dangerouslyAllowMutability: true option to all atoms of the connection instance or atoms that have a nested connection instance (i.e. Anchor's Program class).