# fails to complete a Catalog backup



## mikecox (Nov 19, 2017)

Lightroom version: CC 2015.13 [ 1141928 ]
License: Creative Cloud
Operating system: Windows 10
Version: 10.0
Lr consistently fails to complete a Catalog backup.  The effort ends with as "an error when reading from its preview cache and needs to quit."

I've rebooted my computer and made several more attempts but they all result in the same error.


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## Johan Elzenga (Nov 19, 2017)

That could mean that the previews cache is corrupted, even though you do not see it in day to day work. Open your catalog folder and move the '<catalog name> previews.lrdata' folder to a different location. It doesn't matter where, just move it out of the catalog folder. Start Lightroom. Initially, Lightroom will not show any previews because it needs to rebuild the cache, so you'll see the previews appear one by one. Scroll a few times so Lightroom generates more previews (it only generates previews for visible images), then quit Lightroom and let it make a backup. If this backup succeeds, then it was indeed the previews cache so you can trash the old one.


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## mikecox (Nov 27, 2017)

JohanElzenga said:


> That could mean that the previews cache is corrupted, even though you do not see it in day to day work. Open your catalog folder and move the '<catalog name> previews.lrdata' folder to a different location. It doesn't matter where, just move it out of the catalog folder. Start Lightroom. Initially, Lightroom will not show any previews because it needs to rebuild the cache, so you'll see the previews appear one by one. Scroll a few times so Lightroom generates more previews (it only generates previews for visible images), then quit Lightroom and let it make a backup. If this backup succeeds, then it was indeed the previews cache so you can trash the old one.


Thanks for your response, sorry mine took so long, yours got lost in the shuffle and I had to search to find it!

I did as you suggested but the problem persisted. So I upgraded to Classic CC and converted to the new file format.   Then I opened Lr and closed it again.  This time the backup finished without the error.

I'm a little nervous about opening my other catalog. Will I be automatically prompted to upgrade it?


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## Johan Elzenga (Nov 27, 2017)

mikecox said:


> I'm a little nervous about opening my other catalog. Will I be automatically prompted to upgrade it?



Only when you try to open it in Classic.


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## Linwood Ferguson (Nov 27, 2017)

Remember you can't go backwards, so once you upgrade you need to only use Classic on that catalog.


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## Johan Elzenga (Nov 27, 2017)

Ferguson said:


> Remember you can't go backwards, so once you upgrade you need to only use Classic on that catalog.


True, but the upgraded catalog is a copy, so you will still have the original that you can use to go back.


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## Linwood Ferguson (Nov 27, 2017)

JohanElzenga said:


> True, but the upgraded catalog is a copy, so you will still have the original that you can use to go back.


Of course, I should have elaborated "and any changes you make in the new catalog won't be there if you go back to the original copy". 

Moot of course as there's really no need to, but the reticence in the upgrade spurred the comment.


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## mikecox (Dec 20, 2017)

Thanks for the f\u comments.  I now upgraded to Lr Classic CC both my catalogs are working and backing up.  I will not try to "go back" unless someone is holding a knife to my neck (-:

I will update my Sig now.


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## Linwood Ferguson (Dec 20, 2017)

The old catalog is still there, you might consider renaming itand/or moving it elsewhere so it's never accidentally referenced. 

And if the old preview folder is still there (it likely converted) you can just delete it.

being careful of course to make sure it's the old, not new name you delete.  I always rename my lightroom catalog with each major version just to be certain.


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