DEVONthink claims the database is already in use. How do I overcome?
This can happen when DEVONthink was not quit propely the last time it was used, e.g., due to a crash. Simply click the Ignore button to open the database anyway. If no window appears, open one with File > New Window. If, by any chance, it still doesn’t work, first make sure no incarnation of DEVONthink is runnning. Control-click the database package in the Finder and choose Show Package Contents. In the package, delete the file named DEVONthink.lock. Now, the database should open as expected.