Fix “photos library is in use by another program” Error in OSX Photos

If database repair fails (holding cmd+option on Photos start-up) and you still get the “photos library is in use by another program” error, then you have to manually delete the lockfile.

  1. Find your Photos Library.  Most likely in /Users/[you]/Pictures/Photos Library.
  2. Right-click/ctrl-click the package and select “Show Package Contents”
  3. Navigate to the “database” folder
  4. Delete the “photos.db.lock” file
  5. Restart Photos