Replace-by-fee (RBF)
Also covering BIP125, Opt-in Replace-by-Fee, and Full-RBF
Replace-By-Fee (RBF) is a node policy that allows an unconfirmed transaction in a mempool to be replaced with a different transaction that spends at least one of the same inputs and which pays a higher transaction fee.
Different node software can use different RBF rules, so there have been several variations. The most widely-used form of RBF today is BIP125 opt-in RBF as implemented in Bitcoin Core 0.12.0 and subsequent versions; this allows the creator of a transaction to signal that they’re willing to allow it to be replaced by a higher-paying version. An alternative form of RBF is full-RBF that allows any transaction to be replaced whether or not it signals BIP125 replaceability.
BIP125 requires a replacement transaction to pay both higher feerate (BTC/vbyte) and a higher absolute fee (total BTC). This can make multiparty transactions that want to use RBF vulnerable to transaction pinning attacks, and so an occasional discussion topic is proposals to allow RBF to operate solely on a feerate basis.
Primary code and documentation
Optech newsletter and website mentions
2024
- Bitcoin Core #30592 removes the
mempoolfullrbfsetting - Nodes with full-RBF successfully reconstructing more compact blocks than nodes with only opt-in RBF
- Bitcoin Core #30493 enables full RBF by default
- Question: why does RBF rule #3 exist?
- Bitcoin Core #28984 adds support for a limited version of package replace-by-fee
- Question about the size of transactions that opt-in to RBF, opt-out of RBF, and replacements
- Analysis of how cluster mempool would’ve affected RBF in 2023
- Bitcoin Core #29242 lays the groundwork for package replace by fee
- BitGo adds RBF support
- Pure replace by feerate is not guaranteed to be incentive compatible
- Proposal for replace-by-feerate to avoid transaction pinning
- Idea to apply RBF rules to v3 transactions to allow removing CPFP carve-out for cluster mempool
2023
- Discussion of cluster mempool for RBF
- Summary of well-known behavior for wallets to avoid when creating multiple replacements
- Replacement cycle attacks on HTLCs
- Recommendation to RBF fee bump pre-signed transactions with more pre-signed transactions
- Proposal for miners to automatically retry previously replaced transactions
- Proposal to enable full-RBF by default
- Question about whether 0 OP_CSV forces the spending transaction to signal BIP125 replaceability?
- Suggested best practices for CPFP or RBF fee-bumping a previous CPFP fee bump
- Bitcoin Core #25344 updates the fee-bumping RPCs to allow altering replacement outputs
- Continued RBF discussion, including number of full-RBF nodes, RBF-FSS, and RBF motivation
2022
- 2022 year-in-review: replace-by-fee
- Website to monitor unsignaled transaction replacements
- Continued discussion about enabling full-RBF in Bitcoin Core
- Discussion about
mempoolfullrbfoption’s effect on mempool consistency - Continued discussion about
mempoolfullrbfoption for enabling full RBF - History of the term “full RBF”
- Concerns raised about configuration option allowing full replace by fee in Bitcoin Core
- Proposal for relay of v3 transactions allows replacement
- Bitcoin Core #25610 opts-in the RPCs and
-walletrbfto RBF by default - Bitcoin Core fullrbf setting where the node always allows transaction replacement
- Discussion about enabling full replace by fee in Bitcoin Core (off by default)
- Discussion about allowing transaction witness replacement without a fee bump
- Summary of recent proposed changes to RBF policy
- Discussion about RBF policy, including suggested changes
- Proposal to briefly allow full RBF before using default opt-in RBF
2021
- 2021 year-in-review: default transaction replacement by fee
- 2021 year-in-review: BIP125 opt-in replace-by-fee discrepency
- Proposal of initial RBF rules for mempool package acceptance before implementing package relay
- Trezor wallet software defaults to enabling BIP125 RBF
- Proposal to allow any mempool transaction to be replaced by default
- Continued discussion about CVE-2021-31876’s impact on protocols using RBF
- CVE-2021-31876 discrepancy between BIP125 and Bitcoin Core implementation
- Upcoming relay policy workshop to discuss RBF and other topics
- Recovering lost LN funding transactions after RBF fee bumping
- Question: would first-seen-safe prevent confirmed RBF double spends?
2020
- Sparrow wallet adds support for RBF fee bumping
- C-Lightning #3870 implements RBF scorched earth for penalty transactions
- Bitcoin Core #16373 allows the bumpfee RPC used for RBF to return a PSBT
2019
- Compatibility matrix—Replace by Fee
- Bitcoin Core removes
mempoolreplacementconfiguration option - LND adds support for RBF fee bumping
- Proposal to override some BIP125 RBF conditions
- RBF in the wild (survey of RBF usage)
2018
See also
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