# Ethereum reorganizations: when a recent block leaves the chosen chain A block reorganization occurs when a node’s chosen chain changes and recent blocks are replaced by another accepted branch. Transactions from a replaced block may be included again elsewhere or remain absent; their old receipt position is no longer enough. Check the current chain and finality status, and let applications undo events from removed blocks. Evidence: [Ethereum proof of stake](https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/); [Ethereum JSON-RPC API](https://ethereum.org/en/developers/docs/apis/json-rpc/) Canonical: https://degreesofsatoshi.com/encyclopedia/ethereum-block-reorganizations/ Published: 2026-10-02 Substantively modified: 2026-10-02 Independently verified by an automated reviewer: 2026-10-02T19:27:58.939Z Data current through: 2026-10-02 AI-assisted research and drafting with a separate automated source-verification pass; no external expert or named human review is implied. ## Key facts - **Chain choice:** Consensus fork choice determines the chain head a node follows. ([Ethereum proof of stake](https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/)) - **Receipts:** A receipt identifies the block containing the observed transaction execution. ([Ethereum JSON-RPC API](https://ethereum.org/en/developers/docs/apis/json-rpc/)) - **Logs:** RPC log data can indicate that a log was removed by a reorganization. ([Ethereum JSON-RPC API](https://ethereum.org/en/developers/docs/apis/json-rpc/)) ## Inclusion and durable settlement are different milestones A transaction can first appear in a block near the head while consensus is still developing around that part of the chain. A competing branch can replace that recent inclusion. Finality supplies a stronger consensus milestone than first appearance. Do not describe every wallet notification as irreversible settlement. The strength of the observation depends on the actual block and network state. Evidence: [Ethereum proof of stake](https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/) ## A deposit notification may need to be undone Suppose an application credits a deposit from a newly observed log. That block is then removed by a reorganization. The application must reconcile the credit with the current chain rather than keep treating the removed event as a settled deposit. If the transaction later appears in another block, its new position and execution result should be checked. Re-inclusion is not guaranteed solely because the original signed transaction still exists. Evidence: [Ethereum JSON-RPC API](https://ethereum.org/en/developers/docs/apis/json-rpc/); [Ethereum proof of stake](https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/) ## Track identifiers with their current block context Keep the transaction hash, block hash and log position when processing events. The RPC removed indicator and updated receipts help an indexer distinguish a current event from one belonging to a replaced branch. For material settlement decisions, use the appropriate finalized state and a documented reconciliation policy. This article does not prescribe one universal confirmation count for every application. Evidence: [Ethereum JSON-RPC API](https://ethereum.org/en/developers/docs/apis/json-rpc/) ## Questions ### Does a reorganization mean a transaction signature changed? No. The chain’s inclusion history can change while the signed transaction remains the same. Its accepted block position and result must be checked again. Evidence: [Ethereum JSON-RPC API](https://ethereum.org/en/developers/docs/apis/json-rpc/); [Ethereum proof of stake](https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/) ### Can an application ignore a removed log because it saw it first? No. A removed log describes an event from a block no longer in that accepted chain position. Applications need to reconcile their derived state. Evidence: [Ethereum JSON-RPC API](https://ethereum.org/en/developers/docs/apis/json-rpc/) ## Claims and scope ### ethereum-block-reorganizations-quick-answer A block reorganization occurs when a node’s chosen chain changes and recent blocks are replaced by another accepted branch. Transactions from a replaced block may be included again elsewhere or remain absent; their old receipt position is no longer enough. Check the current chain and finality status, and let applications undo events from removed blocks. Scope: {"collection":"ethereum","dataAsOf":"2026-10-02","blockHeight":null} ### ethereum-block-reorganizations-fact-chain-choice Chain choice: Consensus fork choice determines the chain head a node follows. Scope: {"collection":"ethereum","dataAsOf":"2026-10-02","blockHeight":null} ### ethereum-block-reorganizations-fact-receipts Receipts: A receipt identifies the block containing the observed transaction execution. Scope: {"collection":"ethereum","dataAsOf":"2026-10-02","blockHeight":null} ### ethereum-block-reorganizations-fact-logs Logs: RPC log data can indicate that a log was removed by a reorganization. Scope: {"collection":"ethereum","dataAsOf":"2026-10-02","blockHeight":null} ## Sources - [Ethereum proof of stake](https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/) — ethereum.org contributors. Consensus proposal schedule, voting and finality distinctions. Locator: Slots; epochs; block proposals; attestations; finality. Retrieved: 2026-10-02T18:55:26.560Z. - [Ethereum JSON-RPC API](https://ethereum.org/en/developers/docs/apis/json-rpc/) — ethereum.org contributors. RPC requests explicitly identify addresses and block scope; receipts and removed log fields support verification examples. Locator: eth_getBalance; eth_getTransactionReceipt; block parameter; logs. Retrieved: 2026-10-02T18:55:24.990Z. ## Revision history - 2026-10-02: First publication after primary-source research and separate automated verification. ## Cite this entry Degrees of Satoshi editorial project. “Ethereum reorganizations: when a recent block leaves the chosen chain.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/ethereum-block-reorganizations/