Comment 7 for bug 1812672

Can you share nova.conf of controller? I would say you have configured 'memcached_servers'. Our charm (charm-nova-cloud-controller) is configuring the backend to use 'oslo_cache.memcache_pool' where based on nova/cache_utils.py, the right value nowadays would be 'dogpile.cache.memcached'.

If possible can you update nova.conf like (Please ensure to restart the service):

[cache]
backend = dogpile.cache.memcached

I'm not sure that 'oslo_cache.memcache_pool' is still well maintained.