LR won't open with preferred catalog as "open in another program"

[oddasea]

After a couple of weeks of not using LrC and having backed up each and every time I used it, I got the message that my catalog could not be used, as it was open in another program. Well, it wasn'; there were no other programs open on my desktop. I have resorted to combining an ancient catalog  with my latest backup. It is taking forever. 

Why would it not open the catalog that I wanted? Does it have anything to do with a conflict with Lightroom Mobile perhaps? If it says that in the future, what is the cure?

Thanks in advance....martha m.

[kentdesign]

Did you try restarting your computer and the launching LR by opening the catalog?

[oddasea]

THANK YOU!!!!!  I'll delete that file now!!!!! YAY!!!!!!

[kentdesign · Accepted solution]

I just found this answer from another ACP in this forum:

Using the Windows File explorer or Mac Finder, go to the folder that contains your Lightroom catalog, and delete the file that ends with .lock. Do not delete anything else.

The lock file prevents other users from accessing the catalog, but is normally deleted when you close Lightroom. If Lightroom crashes on exit, has to be force quit, or there is a power failure,  it may not be deleted, which will produce the error message you received.

[Fotosbystu]

Yes! I saw the file and was wondering. Thanks for the clear instructions!  It worked!

[kentdesign]

Hooray! Glad it worked!