What is a blockchain rollback?
A blockchain rollback makes a network continue from an earlier block, removing later activity from the accepted history.
Version 1
GlossaryA blockchain rollback makes a network continue from an earlier block instead of accepting everything that happened after it.
Imagine restoring a saved version of a shared document. The bad change disappears, but legitimate changes made after that save point can disappear too.
A little more technical
Nodes agree to follow a replacement history from a chosen block. Wallets, exchanges and other services then have to compare their records with the new accepted chain. Deposits or withdrawals that existed only in the discarded history may need manual reconciliation.
Common misunderstanding
A rollback does not repair every outside record automatically. An exchange database can still show a balance based on activity that the accepted chain no longer contains.
Source: Zano’s October 2026 rollback postmortem, used here as a current example rather than a universal rule for every blockchain.