I see this in the logs:
Jul 03 16:57:51 pve pvedaemon[3659]: <root@pam> starting task UPID:pve:00002D59:00165C31:5D1D16CF:vzdelsnapshot:100:root@pam:
Jul 03 16:57:51 pve pvedaemon[11609]: <root@pam> delete snapshot VM 100: Before_94_3
Jul 03 16:57:51 pve pvedaemon[11609]: zfs error: could not...