I was using Unity 2019.1 and my project was running fine. After updating Unity to 2019.4 one of the scripts attached to a gameobject give me this warning: "The associated script can not be loaded" and I was not able to use the script.
I have no errors neither in the visual studio nor in Unity. After commenting and uncommenting codes from this script, I figured out what is making this problem: a variable from a library I am using in the project from dll file. (note that some variables from this dll work fine in my script and others are causing this problem).
I tried "Reimport all" and it didn't work.
Can you please help me to solve this problem?
Edit1: