Retry transaction method

[JR0210]

Hi,

I've been working on creating a retry function for buying/selling a token. The buy function can error out on the transaction wait function and never encounters any problems other than issues with gas/slippage which is fine.

Selling seems to encounter a problem though, I'm using a swapExactTokensForTokens function from the Pancakeswap router but each time the sell is called I seem to encounter this error - Error: replacement fee too low, ...., code=REPLACEMENT_UNDERPRICED.

I can see in the docs this can be due to attempting to replace a previous transaction and increasing the gas should work? Though I'm unsure why it would be classified as this since it's called again and the nonce seems different on each attempt?

This is the code for my retry function:

async function retry(fn, n) {
  for (let i = 0; i < n; i++) {
    try {
      console.log(`Attempt ${i+1}`)
      const result = await fn();
      console.log(result, 'Awaiting receipt...')
      const receipt = await result.wait();
      console.log(receipt, 'Receipt');
      if (typeof(receipt) === 'object' && receipt.status) {
        console.log('Transaction receipt');
        console.log(receipt);
        return receipt;
      };
      console.log(receipt, 'Failed');
      throw 'Status Failed';
    } catch {}
  }

  throw new Error(`Failed retrying ${n} times`);
}

Deadline is set to 2 minutes per transaction, gas varies but recently is remaining around 60 gas fee/2000000 gas limit if this helps.

Thanks

[zemse]

You have to increase your gas price enoguh. This section in the docs should help:

When replacing a transaction, by using a nonce which has already been sent to the network, but which has not been mined yet the new transaction must specify a higher gas price.
This error occurs when the gas price is insufficient to bribe the transaction pool to prefer the new transaction over the old one. Generally, the new gas price should be about 50% + 1 wei more, so if a gas price of 10 gwei was used, the replacement should be 15.000000001 gwei. This is not enforced by the protocol, as it deals with unmined transactions, and can be configured by each node, however to ensure a transaction is propagated to a miner it is best practice to follow the defaults most nodes have enabled.

[JR0210]

Thanks :) I did see this section but I'm curious as to why this is classed as a replacement? Doesn't the nonce denote a new transaction which means it's not really a replacement?

Edit: Just to add to this further, this also seems to appear on the first attempt not just subsequent events, the sell order likely only takes place ~30 seconds after the buy but the buy order has been waited for etc.

[zemse]

Are you sure that you're not passing an already used nonce in fn() logic? (because replacement is caused due to nonce reuse)

[JR0210]

No, the retry is only the swapExactTokensForTokens e.g.

const swapTokensForTokens = async (router, amountIn, amountOutMin, tokenIn, tokenOut) => {
  try {
    return await router.swapExactTokensForTokens(
      amountIn,
      amountOutMin,
      [tokenIn, tokenOut],
      data.recipient,
      Date.now() + 1000 * 60 * 2, // 2 minutes
      {
        'gasLimit': data.gasLimit,
        'gasPrice': ethers.utils.parseUnits(`${data.gasPrice}`, 'gwei')
      }
    )
  } catch (err) {
    console.log(err, 'hit err in swapTokensForTokens')
  }
};

Every transaction or receipt console log shows a different nonce too

[JR0210]

I'll try increasing the gas tomorrow on some transactions. If that still fails I'll at least try to get evidence of the nonce changing for each transaction, otherwise I'm not overly sure what's going on with it.

[JR0210]

Attempted today - still the same issue. I'll open this as an issue and reference this. Also added in the gas increase to no avail.