Transaction rollback after a flow error
Key Takeaway
When a flow fails with no fault path, Salesforce rolls back the whole transaction. A fault path turns off that automatic rollback, so use Roll Back Records in screen flows or Custom Error in record-triggered flows to bring it back.
Flows run inside transactions, which group database changes into one unit that either saves together or is reversed together. A rollback stops a half-finished flow from leaving data in a broken state. Where partial completion would cause problems, you need that rollback even on a fault path.
What a rollback does
When any operation in a transaction fails, the entire transaction rolls back. The rollback reverses every database change made in the transaction before anything is committed. It covers Apex triggers, escalation rules, and all flow interviews in that transaction, not just the failing flow's elements.
For example, imagine a flow that updates an account to Active and then creates an onboarding case. If the case creation fails, Salesforce also reverses the account update, because both changes are in the same transaction. Without the rollback, the account would be Active but the customer would have no onboarding case.