I was upgraded to Lightroom Classic 10.00 automatically - Oh dear. I'm running Mojave 10.14.6, daren't upgrade yet to Cataline for fear of more problems. Since the upgrade a few days ago I've had several crashes. Then other problems with collections, essential because I want to use the Book module in a hurry.
When trying to transfer images from the file to a collection I get this message 'An internal error has occurred ?0 attempt to compare two nil values.'
From the forum, it sounds as though this is a bug and I'll have to wait until Adobe fix it.
What about the crashes?
It really is very frustrating - when will these problems be put right.
Also, in this discussion, and in the feedback problem (if you post) include your sys info. Following my SOP for that
Please post your System Information as Lightroom Classic (LrC) reports it. In LrC click on Help, then System Info, then Copy. Paste that information into a reply. Please present all information from first line down to and including Plug-in Info. Info after Plug-in info can be cut as that is just so much dead space to us non-Techs.
Please add your constructive opinion to the bug report, and be sure to click Like and Follow at the bottom of the first post. That will make it a little more likely that Adobe will prioritize a fix, and you'll be notified when the bug's status changes.
As a workaround, select the collection in the Collections panel and do View > Sort to change its sort order to something other than Custom Order.
[Use the blue reply button under the first post to ensure replies sort properly.]