Assembly has reference to non-existent assembly 'Unity.PerformanceTesting'

Question

I'm trying to add ECS to the project. I have added a packages: Entities, Jobs and Collections. But Unity keeps throwing me this error all the time. I have not found a solution to this problem anywhere.

Unity 2018.3.3f1

Error:

Assembly has reference to non-existent assembly 'Unity.PerformanceTesting'
(Packages/com.unity.entities/Unity.Entities.PerformanceTests/Unity.Entities.PerformanceTests.asmdef)

Edit: I found a solution. I had to add to manifest.json

"com.unity.test-framework.performance": "0.1.49-preview"

Answer 1

Maybe for other folks that come over here because of the same problem:

Help -> Reset packages to default.

This resolved the problem for me.