Comment 5 for bug 1903033

I have a reproducer for this and will check it in more detail.

The root cause is that base instance directory /var/lib/nova/instances has the wrong ownership.
It needs to be nova:nova (42436:42436) from nova user inside the container:

[root@overcloud-novacompute-0 instances]# ll /var/lib/nova/
total 0
drwxr-xr-x. 4 root root 32 Nov 19 15:14 instances

Will check on the root cause.