MetaMask Error Code Replacement Transaction Underpriced: How to Fix It

Q: Why does MetaMask require 10% higher gas price to replace transactions?

Ethereum network rules require replacement transactions to have at least 10% higher gas price to prevent spam and ensure miners prioritize the new transaction over the original one.

Q: What happens to the original transaction after speeding up?

The original transaction is replaced and will not execute. Only one version of the transaction will be processed by the network.

Q: How much should I increase gas price to ensure fast confirmation?

Increase by 10-20% for moderate speed, or 50-100% during high network congestion. Check current gas prices on sites like GasTracker before setting fees.

Q: Can I cancel a transaction instead of speeding it up?

Yes, click 'Cancel' instead of 'Speed Up'. Cancellation also requires 10% higher gas price and sends 0 ETH to yourself to replace the original transaction.

Q: Will I be charged twice if I speed up a transaction?

No, you'll only pay gas fees for the successful replacement transaction. The original transaction is cancelled and you won't be charged for both.

Abstract

The 'Replacement Transaction Underpriced' error appears in MetaMask when you try to speed up a transaction but don't increase the gas price by at least 10%. This happens because the new transaction needs a higher fee to replace the original one in the network's memory pool.