Today’s Question: I sometimes get kicked out of Lightroom Classic for no apparent reason. When I try to reopen, I get a screen that says the catalog can’t be reopened because another application already has it opened. But if Lightroom Classic has for sure been closed, how can the catalog be open in another application? Any suggestions?
Tim’s Quick Answer: This issue is most likely the result of a “lock” file being left behind alongside the catalog. Removing that file should enable you to open the catalog in Lightroom Classic again.
More Detail: When you open a catalog in Lightroom Classic, a set of three temporary files are created, one of which is used to indicate that the catalog is in use. The other two are files related to the database the catalog represents. The files should be cleaned up when you quit Lightroom Classic, but they can be left behind if the software crashes. That can lead to an issue where the catalog can’t be opened because Lightroom Classic thinks it is already in use.
In this scenario, you’ll likely find three files in the same folder as the catalog. They’ll have the same base filename as the catalog, with filename extensions of “lrcat-shm”, “lrcat-wal”, and “lrcat.lock”. The last of these is the “lock” file, and its presence will generally prevent you from being able to open your catalog.
Fortunately, you can simply remove this file from the folder with your catalog, and you should then be able to launch Lightroom Classic normally with your catalog. Once that’s the case, you can permanently delete the “lrcat.lock” file that you moved.
Note that the default location for the Lightroom Classic catalog is in a folder called “Lightroom” within the Pictures folder for the operating system. So as long as you’ve left the catalog in its default location you can find it there, but otherwise you can navigate to whatever location you’ve saved your catalog so you can remove the “lock” file.
