Lightroom classic back-up failure

I have been getting this error for a few weeks:

I have checked disc space and have over 2 Tb free.

I have had computer technician give me total access to the drive where catalog has save successfully prior to issue.

I have tried to change drives for the back-up

I have purged cache etc

I have updated to latest release of Windows 11

My LR is up to date.

I have looked through posts here and found one issue which is similar to mine but could not understnd the link to fix.

Obviously something has changed but I have run out of ideas for what to do.

Any ideas please

john