Hello, Rob.
I think I need to find an expert LRC user to help me with this problem. At this point, I'm unable to open Lightroom to reinstall the catalog that was working before the upgrade. Does Adobe offer online help? Where do I go for help?
Thanks in advance,
Lisa Rose
@lisajanrose Did you search your computer for .LRCAT catalog files with Windows File Explorer? What did the search find?
Post us a list of the .LRCAT files you have found.
(In FIle Explorer you need to have file extensions visible- Look in your Folder Options>View. Uncheck "Hide Extensions......")

"Catalogs" do not need to be "re-installed" Catalogs are a database type file that you 'open' with Lightroom-Classic, just as you would 'Open' a word document with MS-Word editor. Re-installing the Lr-Classic App does not affect Catalog files, but an empty Catalog ("connections are gone"?) usually suggests a 'new' catalog has been opened (just like a new word document).
You can select a .LRCAT file and [Right-CLick > Open], or [Double-Click] the file to Open in Lr-Classic.
Regards. My System: Windows-11, Lightroom-Classic 15.6, Photoshop 27.8, ACR 18.7, Lightroom 9.4, Lr-iOS 10.4.0, Bridge 16.0.3 .