.lrcat-data clarifications needed

[nadavr23143382]

Hey,

Found some contradicting information about the folder, so I wanted the expert's advice 🙂

1) Although the Adobe FAQ recommends backing up the folder, and I got an error message stating that  the data is invalid without the folder, I've seen in this post that LRC should be able to recover this information if the folder wasn't backed up with the catalog.
What is true?
2) What exactly are the "AI-based edits" the attached error message refers to?

Any additional information about this folder will be appreciated. Thank you!

[Rob_Cullen]

In simple terms-

2)  Any edits that you do in Lightroom-Classic that involve AI (Artificial Intelligence) eg. Generative Fill, Generative Remove, etc.

1) LrC records the AI edits in the  .LRCAT-DATA folder.  Don't delete the file.

If you backup the Catalog using the Backup dialog when you exit LrC, the created ZIP file contains both the .LRCAT catalog and the .LRCAT-DATA file, so nothing further to be done. (Check this out by looking into a ZIP backup file.)

And https://www.lightroomqueen.com/community/threads/lrcat-data.51796/-  covered these topics well.

[nadavr23143382]

Thanks so much for the info and for taking the time to reply!
Unfortunately, the link you shared seems to be broken - if you have a working one, I’d love to take a look.
Also, I still feel that my original questions weren’t fully answered, particularly about whether Lightroom should be able to recover this data if the folder wasn’t backed up (I’ve read mixed things about this).

One more thing, I also came across some mentions that .lrcat-data can be related to LUTs and/or Look tables. Do you know if that’s the case?
Thanks again for your help, I really appreciate it!

[Rob_Cullen]

Sorry, I unknowingly added a character to the link- The same as you gave it in your first post.

https://www.lightroomqueen.com/community/threads/lrcat-data.51796/

TBMK- Yes, the 'Data' can be rebuilt if the file has been deleted. (Why would you delete it?). And it is automatically included with Catalog Backups when exiting LrC

"related to LUTs" I don't think so- Anything I have seen about LUTs is that they can be used as 'Profiles' in LrC.

LUTS in PS and incorporating them into profiles for Lightroom

[johnrellis]

"I also came across some mentions that .lrcat-data can be related to LUTs and/or Look tables. "

An "enhanced profile" (sometimes called "creative profiles"), a .xmp file that appears in the Profile browser, can contain LUTs. The LUTs get copied into the .lrcat-data file. If you delete the .lrcat-data file, LR will get the LUT from the enhanced profile (.xmp file), as long as it's still accessible.  There's more detail about this in my posts in the long thread that Rob linked to.

[johnrellis]

"whether Lightroom should be able to recover this data if the folder wasn’t backed up"

Yes, LR should be able to recompute the exact AI masks, Generative Remove replacements, and enhanced-profile LUTs if the .lrcat-data file has been removed or not recovered. 

LR sometimes corrupts that file, and a workaround is to delete it, restart LR, select all photos, do Update AI Settings, and then wait a long time while LR recomputes everything. A few people have reported that when they do that, they're not getting back the same exact masks and removes, though I'm mildly skeptical of these reports.