An error occurs when opening a QuickBooks for Mac company data file:
Error: "file [company file name].lock is in use by another copy of QuickBooks", followed by "document [company file name] cannot be opened.
This can occur if the QuickBooks file was not opened completely in a previous attempt, which resulted in the .lock file being created but not automatically deleted.
The .lock file is hidden and cannot be seen using Finder or by navigating to the location. You must delete it using a command line application (Terminal):
Important: Make sure you include the period at the beginning of the file name, otherwise you will not delete the file.