Aurora Postgresql instance flapping with storage "errno = 32"

Have an aurora postgresql cluster that has been down for multiple hours. Tried rebooting instances in the cluster, adding new read replicas and upgrading instances. Nothing seems to work.

One of the existing instances I see the follow log seeming to indicate that the process is flapping. I've done some searching, but nothing seems to document what errno = 32 actually means.

2022-03-31 20:18:43 UTC::@:[18331]:LOG: setting shmemname /mnt/hugetlbfs/aurora-postgres-buffer-cache
2022-03-31 20:18:44 UTC::@:[18331]:LOG: Storage initialization failed. result = 1988, errno = 32
2022-03-31 20:18:44 UTC::@:[18329]:FATAL: Can't handle storage runtime process crash
2022-03-31 20:18:44 UTC::@:[18329]:LOG: database system is shut down

Any idea what's wrong with my cluster and/or how I can fix it?