This was a very scary error to encounter while in the middle of working on a bunch of local changes. If you encounter this, probably don’t panic.

What had happened to me was (I think) related to changing my router settings and what happened was that my hostname was changed from the Mac default of [computer-name].local to [computer-name].socal.rr.com. All while the Sharing panel in System Preferences was showing that the hostname was in fact [computer-name].local.

It took me a while to realize what was going on after fiddling with the filters in P4’s Browse Workspace tool (when P4 first starts up) and using hostname -f in terminal. Thankfully fixing the issue was as easy as changing the computer name to something else and then back to the original computer name in system preferences.

Related article:

How to set the Mac hostname or computer name from the terminal