This issue seems to appear after I have updated to the latest version 2021.2 but I am not sure if this is the cause of my problem.

The problem is that, when I am editing the PHP file, the syntax error doesn't go away even I am very certain that I have fixed the highlighted error.

Here are a few examples:

1. When I write something like $x = 1;, the editor prompts me that the local variable $x is unused. Fine. But this won't go away even I use $x later on.

2. I use the autocomplete feature a lot. So for example when I want to type $this->getSomeObject($id), I can only just type $this->getS and press Enter to let PhpStorm outputs something like "$this->getSomeObject()".

   Now, as getSomeObject() expects a parameter, PhpStorm would underline this line with red, saying that "Required parameter $id is missing". Fine. However, this error won't go away even I fill in the missing piece. Which means that the IDE will still underline the line $this->getSomeObject($id) and complain that I "Required parameter $id is missing".

I see similar problems everywhere in my code, where PhpStorm reports of "unused local variable", "required parameter missing", "undefined variable" etc. never go away. Not even after I reopen the offending file.

Reopening the project can eliminate the outdated error highlights, but similar errors will occur again.

I even try invalidating caches (File/invalidate caches, restart).

An Example :

Version :

PhpStorm 2021.2
Build #PS-212.4746.100, built on July 28, 2021
Licensed to orhan erday
Subscription is active until December 21, 2021.
For educational use only.
Runtime version: 11.0.11+9-b1504.13 amd64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
Windows 10 10.0
GC: ParNew, ConcurrentMarkSweep
Memory: 2996M
Cores: 12
Registry: run.processes.with.pty=TRUE, ide.balloon.shadow.size=0
Non-Bundled Plugins: String Manipulation (8.15.203.000.3), intellij.prettierJS (212.4746.57), de.espend.idea.laravel (0.15.4), de.espend.idea.php.annotation (8.0.0), fr.adrienbrault.idea.symfony2plugin (0.23.210), ru.adelf.idea.dotenv (2021.3.0.212), com.laravel_idea.plugin (4.3.4.212)