After we updated our ceph cluster from 17.2.7 to 18.2.0 the MDS kept being marked as damaged and stuck in up:standby with these errors in the log. debug -12> 2024-07-14T21:22:19.962+0000 7f020cf3a700 1 mds.0.cache.den(0x4 1000b3bcfea) loaded already corrupt dentry: [dentry #0x1/lost+found/1000b3bcfea [head,head] rep@0.0 NULL (dversion lock) pv=0 v=2 ino=(nil) state=0 0x558ca63b6500] debug -11> 2024-07-14T21:22:19.962+0000 7f020cf3a700 10 mds.0.cache.dir(0x4) go_bad_dentry 1000b3bcfea these log lines are repeated a bunch of times in our MDS logs, all on dentries that are within the lost+found directory. After reading this mailing list post <https://www.spinics.net/lists/ceph-users/msg77325.html>, we tried setting ceph config set mds mds_go_bad_corrupt_dentry false. This seemed to successfully circumvent the issue, however, after a few seconds our MDS crashes. Our 3 MDS are now stuck in a cycle of active -> crash -> standby -> back to active. Because of this our actual ceph fs is extremely laggy. We read here <https://docs.ceph.com/en/latest/releases/reef/#cephfs> that reef now makes it possible to delete the lost+found directory, which might solve our problem, but it is inaccessible, to cd, ls, rm, etc. Has anyone seen this type of issue or know how to solve it? Thanks!