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Mac Users on Backing Up: “Your Catalog Size Is Larger than 4 GB”

Mac Users running Lightroom 6.8 or CC 2015.8: have you gone to back up your Lightroom catalog (like I tell you to!), and encountered this message that your catalog is larger than 4 GB, and that you’ll need a third party utility to extract it?

Your Lightroom Catalog Size is Larger than 4 GB

First, as of right now there is a bug – all Mac users are getting this message and most of you don’t have catalogs this large. (Update: this bug was fixed with 6.9 / CC 2015.9 – now you’ll only see the message if your catalog is indeed over 4 GB.) You can check the size of your catalog by going to Lightroom>Catalog Settings – it displays on the General tab:

Lightroom Catalog Settings - Catalog Size

This catalog has information/editing on just a few hundred photos, so it is only 11.54 MB.

Back to the 4 GB warning dialog: regardless of how big your catalog is, consider checking “Don’t Show Again”, and then hit “Continue”  and back up. (Remember, your Lightroom catalog contains all the work you have ever done on  all your photos – so if it becomes damaged and you don’t have a backup, you will most likely lose all that work!)

Here’s the scoop: with Lightroom 6 and CC 2015, Adobe started compressing catalog backups into zip files to make them smaller, and to speed up the backup process. However,  they didn’t do this for catalogs over 4 GB on Mac, since the default macOS unzip utility is unable to unzip files larger than 4 GB. Starting with Lightroom 6.8 / CC 2015.8, Lightroom now will compress these large 4+ GB catalogs, but if you someday encounter a catalog corruption and need to restore from a backup, you’ll need to use a free third party utility such as 7-zip or StuffItExpander to extract it from the zip file. If in doubt, just double-click on the zip file – if it doesn’t open or says that it is corrupted, you’ll need one of these utilities.  However, if you’re lucky and never have a catalog corruption issue, you’ll never need to do this!

Related Posts:

About Your Images and the Lightroom Catalog: The Library Analogy

I Would Cry If I Lost All the Work I Did Today: How to Back Up Your Lightroom Photo Library



2017-06-28T17:48:13-07:00 December 14th, 2016|6 Comments


  1. Bob December 30, 2016 at 9:26 am - Reply

    Thanks for the tip. Checked the size of my catalogue and it was only 622MB in spite of all the pics over the years. Nevertheless until I hear the Adobe has resolved the bug I probably won’t check “Don’t show again” as it is only a minor irritation and am starting to use more video. Q does video increase catalogue size more that Raw pics?

    Keep up the good work


    • Laura Shoe January 5, 2017 at 7:28 pm - Reply

      You’re welcome, Bob. I wouldn’t expect that video would increase the catalog size any more than photos would since the video files themselves aren’t stored in the catalog (as photo files aren’t).

  2. Art Altman December 30, 2016 at 10:01 am - Reply

    Excellent information! Please clarify something important related to backups:

    Are the backups that Lightroom creates individually complete catalogues?
    Or are they incremental?

    That is, for example, suppose I have a dozen backups in the backup folder. I might decide to just retain one backup from December 2015 and then several from recent months. Can I just delete the others without damaging my ability to restore from the other backups?


  3. Judy Leitch January 1, 2017 at 1:45 pm - Reply

    Thank you.

  4. Aysegul Sanford January 5, 2017 at 7:17 pm - Reply

    Thank you for this post. I am getting the same message and was wondering why.
    I also am unable to shoot tethered since the last update. It starts off well but after a I take a few photos, it freezes and then stops recognizing the camera and the exposure values. I wonder if these two are related.
    I did reach out to them and they made me to a few things (like logging off and back on – the usuals), but I am still having the same problem.
    I would appreciate any insight on this. Thank you!

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