Bitcoin stuck in the mempool: RBF versus CPFP
Bitcoin does not have a nonce you can overwrite the way Ethereum does. An unconfirmed transaction sits in the mempool until a miner includes it or nodes drop it. The two legitimate ways to attach a higher fee are replace-by-fee on the original transaction, or a child transaction that pays for the parent.
Neither method is an exchange recovery. If the Bitcoin has not confirmed, the destination has nothing to credit. If it has confirmed, RBF and CPFP are no longer available.
Replace-by-fee
RBF, as Bitcoin Core implements BIP125 opt-in replacement, lets the sender broadcast a new version of the same unconfirmed transaction with a higher fee. Wallets that marked the original as replaceable expose this as speed up or increase fee.
If the original did not signal replaceability, nodes that enforce the policy will reject the replacement. That is not a TXLens setting and not something the receiving exchange can flip.
- BIP125: opt-in replace-by-fee signalling — Primary Bitcoin Improvement Proposal describing when a transaction may be replaced in the mempool.
Child-pays-for-parent
CPFP spends an output of the unconfirmed parent in a new child transaction that pays a high fee. Miners who consider the package may include both. This is the route when you received a stuck payment, or when you sent one that did not signal RBF but you control a change output.
You cannot CPFP a deposit that is already at an exchange if you do not control an output from that unconfirmed transaction. The exchange would have to do it, and they generally will not.
- Bitcoin Core: fee estimation — Upstream documentation on fees and why underpaying leaves a transaction unconfirmed.
What not to do
- Do not create a second independent send of the same amount while the first is in the mempool. Both can confirm.
- Do not pay a 'Bitcoin unlock' service. Unconfirmed is a fee problem, not a freeze.
- Do not open destination-exchange recovery for a hash that has zero confirmations.
What you get, and what it costs
Free, always
The transaction check: network, asset, amount, both addresses, timestamp, on-chain status, confirmation count, and a copyable evidence message for support. No diagnosis.
£9.99, one-off
The diagnosis: the likely cause, recovery outlook, step-by-step instructions, the official support route, wording written for that case, and 72-hour monitoring. No subscription.
Questions
How long should I wait before using RBF?
If the fee is below the current mempool, waiting will not help. Use the sending wallet's speed-up if it offered RBF. If the wallet did not, CPFP from a change output is the remaining honest option.
The exchange says the Bitcoin deposit is pending. Is that RBF?
Usually it means the hash has not reached their confirmation count yet — often one to four blocks in the platforms TXLens tracks. That is a confirmed-but-not-credited wait, not a mempool stuck-send.
Related
Platform requirements on this page were last reviewed 2026-08. They change without notice, which is why every diagnosis is phrased as a likely cause rather than a certainty.
TXLens is read-only. We only use your transaction ID and public blockchain data. We never ask for your private keys, seed phrase or exchange login.