Recovering a Failed IntelliJ IDEA Upgrade with Local History

Context

After upgrading IntelliJ IDEA to 2025.1, the IDE refuses to start and all project settings appear corrupted. The upgrade was performed via the bundled installer, and no manual changes were made to configuration files.

Local History as a Recovery Path

JetBrains documentation states that every change inside the project root, including .idea configuration files, is recorded in .idea/localHistory. Snapshots are retained for 30 days by default but can be increased in Settings → Appearance & Behavior → System Settings → Local History.

Uncertainty

It is unclear whether snapshots captured before the upgrade will survive the failure and whether they can be restored when the IDE itself is non‑functional.

Questions

• Can a user recover corrupted project settings by restoring a Local History snapshot when IntelliJ IDEA fails to launch?
• Which files in the .idea directory are guaranteed to be present in a Local History snapshot?
• Is there a risk of overwriting newer changes if a snapshot older than the upgrade is applied?