Solution has projects that are located outside the solution folder

Question

I tried to add my solution to the local repository by selecting File|Add to Source Control, but I got the following message.

Answer 1

For anyone who experienced this right after adding a xUnit .Net Core test project, the solution/workaround is in a comment from tintow on the excellent answer from dmcquiggin:

I was facing the same problem and found a fairly simple workaround. As dmcquiggen pointed out, this is related to MS Test. I found that by simply unloading the MS Test project before checking in resolved this problem and the test project is still checked into source control. Then just reload the MS Test project and it appears to work as normal. Maybe the underlying test package is not included but thats not a problem for me. – Tintow Oct 11 '19 at 11:59