Failed to create a new snapshot by Snapper

An error occured when creating a new snapshot by Snapper: Failed to create new snapshot: open failed path://.snapshots errno:2 (No such file or directory); caused by 3 sender=:1.138 -> dest=:1.326 serial=184 reply_serial=13 path=; interface=; member= error_name=error.io_error I need some helps.

So - does /.snapshots exist?

Yes, the subvolums under /.snapshots/ can be deleted, but /.snapshots/ can’t be deleted by command-line or YaST-Partitioner. So sad I have reinstalled openSUSE that lost the detail. but I remember it was after switching btrfs quota on/off in YaST-Partitioner that caused the issue.