Backup fails with "EIO: i/o error, close", "uuid is duplicated", "unexpected number of entries in backup cache"

[archw]

And another one.....

For the last week or so, the backup on one particular VM gives this error:

VM2 (xcp-ng-2) 
•	Clean VM directory 
uuid is duplicated
should delete /xo-vm-backups/91bad703-c792-1f05-17a5-042ae49247f7/vdis/371c0511-5058-40bc-b435-3122f21edf50/a888e4cc-19d6-41f4-978a-74bcac97da11/20240509T100018Z.vhd
unexpected number of entries in backup cache
o	merge
Start: 2024-05-12 06:00
End: 2024-05-12 06:00
Duration: a few seconds
Error: EIO: i/o error, close
Start: 2024-05-12 06:00
End: 2024-05-12 06:00
Error: EIO: i/o error, close
•	Snapshot 
Start: 2024-05-12 06:00
End: 2024-05-12 06:00
•	NFS1 
o	transfer
Start: 2024-05-12 06:00
End: 2024-05-12 08:44
Duration: 3 hours
Size: 807.83 GiB
Speed: 84.01 MiB/s
o	Clean VM directory 
uuid is duplicated
should delete /xo-vm-backups/91bad703-c792-1f05-17a5-042ae49247f7/vdis/371c0511-5058-40bc-b435-3122f21edf50/a888e4cc-19d6-41f4-978a-74bcac97da11/20240509T100018Z.vhd
unexpected number of entries in backup cache
Start: 2024-05-12 08:44
End: 2024-05-12 08:44
•	Start: 2024-05-12 06:00
•	End: 2024-05-12 08:44
•	Duration: 3 hours
Start: 2024-05-12 06:00
End: 2024-05-12 08:44
Duration: 3 hours
Type: full

The host is running xcp beta 3 (updated through 5-12-24), XO is version "Xen Orchestra, commit 9b9c7".
This VM and numerous other VM's back up the same way (goes to two different NFS targets) for the last five months.
I've tried running it in the middle of the day (when other backups are not running) but it didn't help.
Backup type = “Delta Backup”
"Number of retries if VM backup fails"=0
"Timeout " = <blank>
"Compression"="zstd"
Any ideas?

[archw]

@archw

Scratch that one.....I should have googled first. I saw that someone suggested deleting the cache.json.gz file. I did and ran it again and it worked.