PyCharm: Errors not flagged and missing import option after update

Problem

After upgrading PyCharm from version 2025.2.5 to 2025.3, errors like undeclared types are not flagged, and the option to import types by hovering over them and selecting "import" is missing.

Cause

Potentially caused by outdated or corrupted IDE caches.

Resolution

Invalidate the IDE caches by performing the following steps:

1. Navigate to File | Invalidate Caches | Invalidate and Restart in the PyCharm menu.
2. Confirm the action and let the IDE restart.