Customer got this error.
QuickBooks is unable to open this company file. It may have been opened by another user.
We had all the users log out, but the single user trying to get was getting the error.
What I did to fix it was to log onto the server, run services, and restarted all the quickbook services.
- QBCFMonitorService – This service was not running though set to start automatically. Starting this service got it working correctly.
I hope this helps someone else out there…