Visual Studio can't attach to Unity "Operation could not be completed"

Question

This was working last night. I've loaded up Unity today, made zero changes that could cause something like this to happen and it's just stopped working for no reason.

"Attach to Unity" doesn't work, "Attach to Unity and Play" doesn't work.

How do I fix this? There's no information on Google and zero helpful information in the error message.

Answer 1

I had this problem and no closing, restarting VS or Unity would help. Then I found this post: https://developercommunity.visualstudio.com/t/the-operation-could-not-be-completed-unspecified-e-4/1654024 It mentions network interfaces for virtualization systems. I had a HyperV machine running in the background so I shut it down and restarted VS. The debugger connected immediately.