Hello, Quite an hold thread, but maybe this will help someone. We had the same issue on our Ceph cluster. It all came down to an erasure code profile with a missing setting. In the logs of ceph-mgr (journalctl -xru ceph-mgr@<host>.service), we saw the following error: KeyError: 'm' description = f"ec:{profile['k']}+{profile['m']}" in /usr/share/ceph/mgr/prometheus/module.py. One of our erasure code profile was missing the setting "m" (which is the number of parity chunks for a chunk of data, if I understood correctly). You can see your erasure code profile using : ceph osd erasure-code-profile ls And the settings of each code profile with : ceph osd erasure-code-profile get <name> We deployed a simple fix by editing the module.py file to handle this scenario. Replace (around l.1250) if profile: description = f"ec:{profile['k']}+{profile['m']}" With if profile: if profile.get("m", None) is not None: description = f"ec:{profile['k']}+{profile['m']}" else: description = f"ec:{profile['k']}" Adrien [Site du CEA]<https://www.cea.fr/> Adrien JOUSSE Ingénieur systèmes Unix Direction de la Recherche Fondamentale (DRF) DRF/IRFU/DEDIP//LIS Centre de Saclay [Facebook]<https://fr-fr.facebook.com/cea.pageofficielle> [Youtube] <https://www.youtube.com/channel/UCpTMWY8NRQby8zXUKhHznfg> [Twitter] <https://twitter.com/CEA_Officiel> [LinkedIn] <https://fr.linkedin.com/company/cea> [Instagram] <https://www.instagram.com/cea_officiel/>