Handling Stuck Ethereum Transactions

31 Mar 2021

The code snippets in this post use web3.js, decimal.js and assume that you are connected to a geth node.

Stuck Transactions on Eth

If you have seen and experienced something similar to the screenshot, then you know what I’m talking about. :)

Why are they stuck?

• Because the gas price fluctuates and the gas price specified in your transaction is lower than the accepted average at the time.
• Gas price is ok, but there is a pending transaction with lower nonce on the account.

What is gas & gas price?

The gas value of a transaction tells miners how much computational resources will be needed to mine the transaction.
The gas price tells miners how much Ether you’re willing to pay for the unit of work (gas).
Therefore, this is how the transaction fees are calculated in a nutshell: gasNeeded * gasPrice .

The solutions

Try to calculate optimal gas prices to avoid transactions getting stuck

This is the first step in fixing the problem for future transactions. For this purpose you could use:

• Etherscan’s gas tracker API
• Record gas prices from last N blocks, calculate the average and add a small cushion.
• Or If you don’t care too much about the fee amount and just want to transfer a quickly as possible, just multiply the gasPrice received from your ethereum client by some number.

Note: The methods below do not guarantee that the last submitted transaction will be processed. It just increases the probability! Therefore, for reliable transaction handling, every transaction has to be tracked!

Replace pending transaction with same transaction but with higher gas price

As you might have seen Ethereum transactions that belong to one account execute in strict order. This order is controlled by the nonce value of the transaction.
In order to increase the probability of a transaction getting confirmed you can:

• Fetch the transaction data with

  const transaction = await web3.eth.getTransaction(transactionHash);
  

• Send the transaction again, but this time increase the gasPrice by 10%:

  const hash = await web3.eth.personal.sendTransaction({
    from: transaction.from,
    to: transaction.to,
    // Use decimal to avoid any precision errors. Gas price is specified in wei, so it must be an integer
    gasPrice: Decimal.mul(transaction.gasPrice, 1.1).round().toNumber(), 
    gas: transaction.gas,
    value: transaction.value,
    data: transaction.input
  }, 'MyPassword!'));
  

FYI, Some refer to this as a ‘speedup’ transaction.

What if I don’t want to send it anymore?

Similarly you can:

• Fetch the transaction data with

  const transaction = await web3.eth.getTransaction(transactionHash);
  

• Send the transaction again, but this time set value to 0 and increase the gasPrice by 10%:

  const hash = await web3.eth.personal.sendTransaction({
    from: transaction.from,
    to: transaction.to,
    // Use decimal to avoid any precision errors. Gas price is specified in wei, so it must be an integer
    gasPrice: Decimal.mul(transaction.gasPrice, 1.1).round().toNumber(), 
    gas: transaction.gas,
    value: '0',
    data: transaction.input
  }, 'MyPassword!'));
  

FYI, Some refer to this as a ‘cancel’ transaction.