after the last update to LRC 26.6.2, backups fail everytime.

Failing catalog backups are reported from time to time. This is almost always caused by catalog corruption. You can usually fix this as follows: Create a brand new catalog (‘File - New Catalog’) and choose 'File - Import from Another Catalog'. Select your old catalog to import. In the import dialog choose to import all photos, but do not move them. This will create an exact copy of your old catalog, but without the corruption. The only thing that won't come across is any publishing services you may have. You will have to recreate those. If you synced your catalog then you will have to enable sync for the new catalog. There are some reports that this could cause a problem. Here’s how to solve that: https://www.danhartfordphoto.com/blog/2025/1/lr026-fixing-sync-problems-caused-by-switching-the-sync-catalog