How would I roll back a bad deployment?

Short explanation:

Rollback restores a previously working application version after a harmful release. It works only if that version is compatible with the current database, message formats and configuration. A complete rollback plan includes health verification and a way to preserve or reconcile work already performed by the new version.

Key points:

• Restore the previous known-good artifact and verify health and user flows.

• Check whether database changes are still compatible with the old app.

• Prefer backward-compatible schema changes so rollback does not require deleting data.

• Keep versioned artifacts and backward-compatible migrations so the old application can still run during recovery.

Interview point:

• “Deploy the old image” is only one step; explain compatibility and post-rollback validation.