I spent quite a while earlier trying to make an RDP connection to another system on my network. The error message from the RDP client was:
Your computer could not connect to another console session on the remote computer because you already have another console connection in progress.
You can imagine the range of things I tried to resolve the issue.
The actual issue? The machine had a new IP address and I was trying to connect to its old IP address. Great error message 🙁