I’ve had this problem before and fixed it, but for the life of me can’t find the solution again.
In short, the Asset Server has seemingly randomly stopped working. I can’t connect to it from the Editor (“server closed the connection unexpectedly”) and when I try to reset the admin password from AssetServerControl it complains that psql.exe does not exist, despite the fact that it does.
I remember that this was something to do with the user UnitySrv. I do have an account UnitySrv on this PC, but it’s hidden and I can’t figure out how to access it.
And that’s about as far as I’ve got.
Edit: Oh, I’ve got other projects hosted on Linux servers and I’ve never had a problem with those. It’s just the local install I have on my workstation which gives me grief.
Update 2, and a fix
Ok, found the issue. It’s that the service wasn’t running under the correct username. To fix it:
1: Go to the Services control panel. (Start → type “Services” → press Enter.)
2: In the Services panel, scroll down to Unity Asset Server. Double click it.
3: Open the “Log On” tab. The user should be “unitysrv” or “./unitysrv” or similar. If it’s not, set it to that with the appropriate password. Note that I don’t know what the default password is. I vaguely remember creating the account myself last time I had this problem, but I know you shouldn’t have to do that…
4: Restart the service.
5: If, like me, a dialog pops up and says that the service immediately closed, restart the computer.
Step 5 doesn’t really bother me in this case since it’s my workstation, not a dedicated server. If this happened on one of my dedicated servers it’d irritate me, though, because having to restart it would potentially mean kicking people off other services temporarily.