My PhpStorm 5 does not know php native functions

Question

I recently downloaded PhpStorm 5. Everything work fine with verion 4, but now I can not access to native php functions on autocomplete. Functions and classes declared in my

Answer 1

How sj59 answered higher if you had used multiple versions of Phpstorm on Ubuntu like 2020.1, 2020.2 and then 2020.3 deleting cache can help but it was not working for me until I deleted all JetBrains Cache folder like this:

rm -rf ~/.cache/JetBrains/

Before this I tried Invalidating Caches, turning all plugins off and reinstalling the IDE completely