Test Explorer (VS) shows '<Unknown project>'

Solution 1:

1. Close Visual Studio.
2. Delete the *.testlog files in: solutionfolder\.vs\solution name\v16\TestStore\number.

Solution 2:

I faced the same issue right now. A cleanup helped. As I had cleanup issues with VS in the last time (some DB-lock prevents a real cleanup to happen), my working cleanup was this way:

1. Close VS.
2. Git Bash in solution folder: git clean -xfd

Probably it helps.

Solution 3:

Neither of these solutions worked for me. I was able to get the test explorer working by closing visual studio and deleting the ".vs" folder. Then reopen the solution and let it rebuild it.

Solution 4:

According to the Visual Studio developer community (found by going to the Help menu and selecting Feedback), an update to Visual Studio to version 16.5.5 will resolve the issue. FYI: They released this in February 2020

I can confirm it works (I was on VS 16.4.6)