Invalidate caches
PhpStorm caches a great number of files, therefore the system cache may become overloaded. Sometimes the caches will never be needed again, for example, if you work with frequent short-term projects.
When you invalidate the cache, PhpStorm rebuilds all projects ever run in the current version of the IDE.
Note the following before you proceed:
The caches will not be deleted until you restart PhpStorm.
Opening and closing a project without invalidating the caches does not result in deleting any files.
Local History is not deleted when you invalidate the caches. However, mind that Local History has a retention period of 5 working days.
Clear the system cache
From the main menu, select .
In the Invalidate Caches dialog, select an action. You can invalidate the caches and restart the IDE or just restart the IDE.
For details on where various user-specific files are stored, see Default IDE directories.