# Lightroom catalog cannot be opened because



## Kris

Hi all, 
I'm encountering an issue opening Lightroom with error message saying 'The Lightroom catalog named "Lightroom 5 Catalog" cannot be opened because another application already has it opened.' When I click to open Lightroom this shows up, and then multiple applications of Lightroom keep opening themselves & showing the same message until I force shut down the computer. 
I've searched my mac for a .lrcat.lock file to delete however nothings showing up, just the normal catalog.lrcat file. 
Before this error showed up, my Lightroom storage was full so I was trying to clear out space - not sure if I've accidentally done something to cause this? 
I'm not very tech savvy so any help is well & truly appreciated  
Thank you, Kris


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## clee01l

Welcome to the forum. 
What has happened is the last time LR did not shut down properly.  Perhaps your computer crashed or there was a power failure.   When LR opens your catalog file it creates a sentinel file in the same folder as the catalog so that two instance of LR can not open the same catalog file.   Open your Lightroom folder in Finder and look for a file alongside your catalog file with the same name  as the catalog but with an extension of ".lock". Delete this ".lock" file and you will be able to open LR normally.


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## Kris

Thank you for your help. There's no .lock file with my catalog file though and I've tried searching my finder folder for that extension but nothing is showing up. 
Would it be worth reinstalling Lightroom on my computer? I've not done this before so not sure if you lose your work? 
Thanks, Kris


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## Rob_Cullen

Kris said:


> Thank you for your help. There's no .lock file with my catalog file though and I've tried searching my finder folder for that extension but nothing is showing up. :(
> Would it be worth reinstalling Lightroom on my computer? I've not done this before so not sure if you lose your work?
> Thanks, Kris


Backup you Catalog and photos. Re-installing Lightroom does not affect these, but-
In the absence of a 'Lock' file, your problem of "multiple applications opening" sounds similar to another forum thread at- Multiple (and more and more) instances of LR st... | Adobe Community
Possibly the best answer in that thread might be from Chadwick110 in Post#22
Other suggestions there included - Permissions in folders, and problems with Sign-in Activation.


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## Kris

Thank you, I followed Chadwick110's steps and it appears to have worked! 
Really appreciate your help.


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