Local Catalog Damaged

TL,DR: Uninstall Lightroom CC. Delete the entire Lightroom CC folder from "C:\Users\<Username>\AppData\Local\Adobe". Reinstall Lightroom CC from Creative Cloud. Let it sync.

I was struggling with this exact issue for a couple of days now. I did Adobe's solution of changing the MCAT file and deleting the previews folder/file. I uninstalled and reinstalled the application multiple times. I restarted the computer. I signed in and out of my account. I read countless forums. I could access the photos from LR's web version of the site, but the website just isn't as intuitive as the local application. I was at my wit's end and was about to just cancel my subscription and look for a new photo editing software to use. Then I hit this thread. I tried the solution by Sameer and noticed the Lightroom CC did work in the Administrator account. When I returned to my main account, however, the same error message appeared. Something clicked in my brain, and I decided to uninstall the app and delete the ENTIRE Lightroom CC folder from C:\Users\<Username>\AppData\Local\Adobe. I didn't just delete those specific files that Adobe kept telling me to delete. I deleted the entire folder. I reinstalled Lightroom and held my breath as the app finally loaded. It's taking some time to sync now, but it's FINALLY working. A new Lightroom CC folder appeared in my C Drive as well. 

I know that the person who wrote the original post stated that he just waited it out and it worked, but I just wanted to offer up my solution in case anyone else is struggling like I was. Hopefully this helps!

Hey @Howard Bck. Welcome to the Lightroom Community. I'll help you figure this out.

You've already tried this step, just to be sure, try this way again:

Go to the following location

• C:\Users\<Username>\AppData\Local\Adobe\Lightroom CC\Data
• Press Windows + R key to open the Run dialogue & type this location
  
  %localappdata%\Adobe\Lightroom CC\Data
  
  

   

• You'll find a folder inside it with a long cryptic string of numbers and letters (for example, d1a4f88d2b534c7d91022136fd182532). Open that folder.
• In the folder, delete all the files named Managed Catalog.[anything]. Also, delete the Previews.db file.
• Launch Lightroom.

If the issue still exists, try creating a new user account by following these steps & check how it goes:

• In Windows, search for CMD > right click & Run as administrator. (It should say C:/Windows/System 32)
• Type in or copy 'net user administrator /active:yes' & the command should run successfully.
• Sign out of the current user & sign in to the administrator profile.
• Recheck Lightroom.

You can sign back into the original user & deactivate the admin user account by entering CMD again.

• net user administrator /active:no

Let me know how it goes,

Thanks!

Sameer K