Also add the question: Are the CEPH perhaps so busy deleting other VM's data that it can't handle this deletion request?"Do you have the keyring for the pool in place? If you disabled ceph auth, then you also need to remove the keyring for the storage.
https://pve.proxmox.com/pve-docs/chapter-pvesm.html#_authentication
Just had the exact same error... and after the big boy's deletion where done, and the ceph "stabilized" things just "work(TM)" again
root@quesadilla:~# pct list | grep -i itc| grep stopped | awk '{print "pct destroy "$1" --purge 1 --destroy-unreferenced-disks 1"}'|bash -x
+ pct destroy 10301101 --purge 1 --destroy-unreferenced-disks 1
purging CT 10301101 from related configurations..
+ pct destroy 10301104 --purge 1 --destroy-unreferenced-disks 1
purging CT 10301104 from related configurations..
+ pct destroy 10301105 --purge 1 --destroy-unreferenced-disks 1
rbd error: rbd: listing images failed: (2) No such file or directory
+ pct destroy 10301106 --purge 1 --destroy-unreferenced-disks 1
rbd error: rbd: listing images failed: (2) No such file or directory
+ pct destroy 10301108 --purge 1 --destroy-unreferenced-disks 1
rbd error: rbd: listing images failed: (2) No such file or directory
root@quesadilla:~# pct list | grep -i itc| grep stopped | awk '{print "pct destroy "$1" --purge 1 --destroy-unreferenced-disks 1"}'|bash -x
+ pct destroy 10301105 --purge 1 --destroy-unreferenced-disks 1
rbd error: rbd: listing images failed: (2) No such file or directory
+ pct destroy 10301106 --purge 1 --destroy-unreferenced-disks 1
rbd error: rbd: listing images failed: (2) No such file or directory
+ pct destroy 10301108 --purge 1 --destroy-unreferenced-disks 1
rbd error: rbd: listing images failed: (2) No such file or directory
root@quesadilla:~# pct list | grep -i itc| grep stopped | awk '{print "pct destroy "$1" --purge 1 --destroy-unreferenced-disks 1"}'|bash -x
+ pct destroy 10301105 --purge 1 --destroy-unreferenced-disks 1
purging CT 10301105 from related configurations..
+ pct destroy 10301106 --purge 1 --destroy-unreferenced-disks 1
purging CT 10301106 from related configurations..
+ pct destroy 10301108 --purge 1 --destroy-unreferenced-disks 1
purging CT 10301108 from related configurations..
root@quesadilla:~#
+ pct destroy 10301101 --purge 1 --destroy-unreferenced-disks 1
purging CT 10301101 from related configurations..
+ pct destroy 10301104 --purge 1 --destroy-unreferenced-disks 1
purging CT 10301104 from related configurations..
+ pct destroy 10301105 --purge 1 --destroy-unreferenced-disks 1
rbd error: rbd: listing images failed: (2) No such file or directory
+ pct destroy 10301106 --purge 1 --destroy-unreferenced-disks 1
rbd error: rbd: listing images failed: (2) No such file or directory
+ pct destroy 10301108 --purge 1 --destroy-unreferenced-disks 1
rbd error: rbd: listing images failed: (2) No such file or directory
root@quesadilla:~# pct list | grep -i itc| grep stopped | awk '{print "pct destroy "$1" --purge 1 --destroy-unreferenced-disks 1"}'|bash -x
+ pct destroy 10301105 --purge 1 --destroy-unreferenced-disks 1
rbd error: rbd: listing images failed: (2) No such file or directory
+ pct destroy 10301106 --purge 1 --destroy-unreferenced-disks 1
rbd error: rbd: listing images failed: (2) No such file or directory
+ pct destroy 10301108 --purge 1 --destroy-unreferenced-disks 1
rbd error: rbd: listing images failed: (2) No such file or directory
root@quesadilla:~# pct list | grep -i itc| grep stopped | awk '{print "pct destroy "$1" --purge 1 --destroy-unreferenced-disks 1"}'|bash -x
+ pct destroy 10301105 --purge 1 --destroy-unreferenced-disks 1
purging CT 10301105 from related configurations..
+ pct destroy 10301106 --purge 1 --destroy-unreferenced-disks 1
purging CT 10301106 from related configurations..
+ pct destroy 10301108 --purge 1 --destroy-unreferenced-disks 1
purging CT 10301108 from related configurations..
root@quesadilla:~#