Resolving Stuck Transactions with CPFP and Replace by Fee
Transactions that have been sent to the blockchain may sometimes remain pending for an extended period when the transaction fee is too low to make them attractive for inclusion in a block. In these cases, the transaction is not necessarily failed, but it can become effectively stuck until network conditions change, the transaction is dropped from the mempool, or a fee-bumping mechanism is used to encourage miners or validators to process it.
This page describes the supported methods for releasing stuck transactions in the system. For most EVM-based networks and supported currencies, stuck transactions can be released using the Replace By Fee flow, which replaces the pending transaction with a new version that uses a higher fee. For Bitcoin-based transactions, the system supports the Child Pays for Parent flow, where a new child transaction is created with a higher fee to incentivize confirmation of both the child and its unconfirmed parent transaction.
This article describes the two different processes to release these transactions:
- Child Pays for Parent - for Bitcoin-based transactions
- Replace By Fee - for other EVM-based transactions
Child Pays for Parent
To release a Bitcoin transaction, add a new transaction is associated with the existing stuck transaction.
The original transaction is called the 'Parent' and the new one with the additional fee, tied to the original transaction, is called the 'Child'. Because the child transaction depends on the parent transaction, miners must include the original parent transaction before they can include the child transaction. The higher fee on the child transaction increases the effective combined fee rate of both transactions, encouraging miners to confirm them together in a block on the blockchain.
To unblock the BTC transaction:
Open the Transaction Page and locate the BTC transaction that appears to be stuck and expand the transaction details.
Select Click to update the fee to add a second transaction to this one.
The Update Fee Structure window opens. This window shows the Suggested fee for the transactions and lists all stuck, sent transactions that are not being confirmed on the blockchain.
For BTC transactions, each transaction is considered separate from another and are not held up because of an earlier transaction. Therefore, a later transaction can be changed without needing to ensure that earlier, stuck transactions have been released.
The Suggested fee is listed at the top of the window. This fee can be accepted for all of the transactions or custom fees can be set for each transaction.
Select Create CPFP Transaction to accept the current suggested fee and apply to all of the transactions.
Select Set custom fees to set your own fees.
When selecting Set custom fees the values become editable and can be updated.
Once the Custom fee is set, select Create CPFP Transaction to send this transaction to the blockchain.
Check the Transaction History page for the transaction details to update.
Replace by Fee
To release an EVM-based transaction, adjust the fees given to the original transaction and then resubmit the original transaction to the blockchain.
The new transaction is created with the same nonce or transaction sequence as the original pending transaction. As the replacement transaction uses the same transaction ordering identifier, the network treats it as a replacement for the original transaction rather than as a separate additional transaction.
Once the replacement transaction is broadcast to the network, miners or validators are incentivized to include the higher-fee version in a block. When the replacement transaction is confirmed on the blockchain, the original pending transaction is effectively canceled or overwritten, since only one transaction with that nonce or sequence can be confirmed.
Any transaction that is sent after the stuck transaction also remains stuck, even if its fees are above current suggested fees. This is because all transactions with a higher nonce are held up until the lowest nonce is accepted on the blockchain. This means that the list of transactions might also include transactions that would otherwise be accepted based on their current fees.
To Replace by Fee:
Open the Transaction Page and locate the transaction that appears to be stuck and expand the transaction details.
Select Click to update the fee to increase the fees for this transaction.
The Update Fee Structure window opens. This window shows the Suggested fee for the transactions and lists all stuck, sent transactions that are not being confirmed on the blockchain. This includes all transactions with a higher nonce than the stuck transaction as they are also held up until this transaction is released.
Suggested fees are listed at the top of the window. These fees can be accepted for all of the transactions or custom fees can be set for each transaction.
Select Replace by fee to accept the current suggested fee and apply to all of the transactions.
Select Set custom fees to set your own fees.
When selecting Set custom fees the values become editable and can be updated.
Additionally, a Suggested gas option appears at the top of each transaction, and on mouse hover over, a pop-up window displays gas fees to apply to the transaction by selecting Apply.
When all transactions are updated, select Replace by fee to send the updated transaction to the blockchain.