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Yukon Dan
Yukon Dan
Inspiring
September 10, 2026
Question

Lightroom takes several hours to open a catalog.

  • September 10, 2026
  • 3 replies
  • 28 views

A couple of months ago, I went to open a Lightroom Classic catalog, and it appeared to crash. The first Lightroom graphic appeared, but after a few minutes, the catalog didn’t open. At first, I force-quit and tried again. That didn’t help. Then I resorted to pulling an old catalog file from Time Machine, which worked initially but later failed the same way after closing the catalog and reopening. It wasn’t always immediate. Sometimes I could close the catalog and reopen it right away, and it would work, but eventually it failed the same way again. 

 

I dug around in the Lightroom community and found many other people having similar issues, but most seemed to be using Windows 11. People said Lightroom would eventually open if you left it long enough. Several hours!

 

I tried this and found that it was true. Whenever the catalog seemed to crash while trying to open, if I left it for hours, it would eventually open. In all of these other posts by other people with similar issues, one of the community mods chimed in and said to just leave it; it would eventually open, and then the problem would be gone. 

 

The problem is that this isn’t the case for me. Even if I leave my catalog to go through the many-hours-long opening process, it eventually fails again. Sometimes the same day. 

 

I’m running Tahoe 26.6.2 on an M1 Max Mac Studio. The problem started so long ago that I have now experienced it on several versions of Lightroom Classic. I’m currently up to date on version 15.5.1 and still have the same issues.

 

One strange thing I have noticed is that while the catalog seems to be trying to open, going through this several-hour opening process, my external drive containing my image archive is being accessed heavily. I can hear all the drives in my external RAID working hard and being accessed, even while no other applications on my Mac are using those files. It seems like Lightroom is accessing all the files in the catalog for some reason.

 

The second strange thing is that if you open Activity Monitor while the catalog appears to have crashed on opening, it lists Lightroom as actively using a huge proportion of my CPU. So, while a right-click on the Lightroom app in the dock shows “Application Not Responding”, the Activity Monitor and the disk access clearly show Lightroom is active in the background in some way.

 

I tried to eliminate several possible issues:

  • I trashed the Apple preferences files - this didn’t solve the issue
  • I trashed the Lightroom preferences
  • I reverted to old catalog backups to rule out the fact that my catalog had become corrupted. This didn’t help. The opened backup catalog would eventually run into the same issue.
  • I disabled all plugins in Lightroom Classic
  • When I had a catalog that was open, I ran the catalog optimization tool. This didn’t help.
  • Since opened catalogs all seem to fail again at some point, I have tried to figure out what action I might be taking that could cause this failure. Such as, does it fail after doing a catalog backup on exit. The problem is that the whole testing process takes days because each time it takes a day to reopen a busted catalog. I’m lost, and sometimes the catalogs just seem to break without me performing a specific task. One minute you can close and reopen the catalog just fine, the next time you open it, it takes all day to open again. 

 

 

    3 replies

    Yukon Dan
    Yukon DanAuthor
    Inspiring
    September 11, 2026

    One hypothesis I have is that the issue is caused by the option to write changes to an external XMP file. I’d love someone else to test this theory if they are also having trouble.

     

    Here’s how I tested this.

     

    • Try to open a catalog that is seemingly “broken”
    • Leave it running all day, and eventually the catalog opens (after about 12 hours for me). YMMV.
    • Test the catalog by closing it, then opening it. 
    • Confirm there is no delay in opening.
    • Catalog appears “fixed”
    • Perform a large bulk edit to a number of images
    • After applying the edit, immediately close Lightroom
    • If you have the “write changes to XMP” option enabled, Lightroom should pop up a warning that not all changes have been written to the XMP files and the process will continue next time you open Lightroom. Continue to exit Lightroom by pressing the “Quit” button
    • Try opening the catalog again right away.
    • For me, this appears to revert the catalog back to its “broken” state, and it then takes about 12 hours to open again.

     

    There are many variables, and I cannot yet be 100% certain that quitting while LR is writing XMP changes causes this issue. But it’s currently the best lead I have.

     

     

     

     

    Califdan2
    Califdan2
    Inspiring
    September 10, 2026

    May not relate, but on Windows, many times when you try to launch LrC it doesn’t seem to do anything, so you try again it leaves debris.  I've seen this serveral times where a “Rename Catalog” command renames the catalog but fails to automatically re-launch LrC with the newly renamed catalog. But I’ve also seen this in situaitons not related to a catalog rename.

    In most cases it leaves the “lock” file in place which exacerbates the problem by silently refusing to open LrC (when that catalog is the dafault catalog) on subsequent attempts.  In the past we used to get a pop up saying something like “catalog in use and can’t be opened” but we don’t seem to get that message anymore.

    The other thing is that in Windows Task Manager it leaves a “Lightroom Classic” process running which seems to be doing something as the numbers under CPU usage, Memory Usage, and Disk Usage keep changing;.  Each attempt to launch LrC adds yet another of these processes and you can wind up with quite a collection of them.

    I have found that deleting the “.lock” file and ending those “Lightroom Classic” processes using Task Manager many times allows LrC to open normally.   

    What, if anything, this has to do with the several hour launch times noted in this thread I can’t say.  But one thought is that these background processes may eventually finish whatever they were doing at which point the last one standing goes ahead and launches LrC.

      Yukon Dan
      Yukon DanAuthor
      Inspiring
      September 11, 2026

      Thanks for highlighting the lock file. I forgot to mention this in my write-up. I've tried deleting the lock file if it gets left behind, but it didn’t resolve the issues I have experienced. 

       

      On a Mac, at least, the additional processes don't seem to be an issue. Activity Monitor shows a single instance of Lightroom.

       

      I wonder why my post was changed from a bug report to a question? With so many reports of this already on the forum, it sure seems like a bug. 

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