Garmin connect does not sync

My Edge 800 has been used satisfactorily for many years but now when I connect to PC by USB cable I initially get a message

"Synced just now"

and when I click to Sync again after some delay I get a message

"There was an error syncing with Garmin Connect"

I tried deleting some records although SD card is not full.

I have tried over several days in case it was a problem with the website but still no joy.

Any suggestions please?