After updating unity 2019.1.4f1 to 2019.4.0f1, 445 errors NUnit type or namespace not found, anyone can help me?

Library\PackageCache\com.unity.test-framework@1.1.14\UnityEngine.TestRunner\Assertions\AllocatingGCMemoryConstraint.cs(2,7): error CS0246: The type or namespace name ‘NUnit’ could not be found (are you missing a using directive or an assembly reference?)
this kind of 445 erros are there.

unity game engine - Unity3D Package Cache errors(?) - Stack Overflow this may be help also, i try both solution, one given by @okcompute_unity and above link and now working correct for my project. all error gone I had updated from unity 2019.1.4f1 to unity 2019.4.0f1 LTS and error comes.
Thanks @okcompute_unity

Another link for “Unity 2017.2.0f3 Resolving Package Error” here for answer worked for me for Unity 2019 version. thank all.

Reimporting all assets (right click in project folder → Reimpart all) solved it for me, thanks!

This is because in the new update, unity automatically adds a directive.

If you are not familiar with what the directive is, it’s just the little text at the very top of the page such as

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

//etc

Unity is basically giving you a useless directive which is:

using NUnit;

just delete this line of code Unity puts for you and your code should now execute without any problems. (¬‿¬)