I hate to be the one to say "me too", but... Seems like a couple of people have received this error here in the support thread. Not seeing a solution yet. The above Quote is pretty much exactly what I am seeing.
I am also running unRaid 6.8.3.
Errors from the logfile mentioned in the unRaid log.
2020-09-20 8:28:02 0 [Note] InnoDB: Using Linux native AIO
2020-09-20 8:28:02 0 [Note] InnoDB: Uses event mutexes
2020-09-20 8:28:02 0 [Note] InnoDB: Compressed tables use zlib 1.2.11
2020-09-20 8:28:02 0 [Note] InnoDB: Number of pools: 1
2020-09-20 8:28:02 0 [Note] InnoDB: Using SSE4.2 crc32 instructions
2020-09-20 8:28:02 0 [Note] mariadbd: O_TMPFILE is not supported on /tmp (disabling future attempts)
2020-09-20 8:28:02 0 [Note] InnoDB: Initializing buffer pool, total size = 134217728, chunk size = 134217728
2020-09-20 8:28:02 0 [Note] InnoDB: Completed initialization of buffer pool
2020-09-20 8:28:02 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. S
ee the man page of setpriority().
2020-09-20 8:28:02 0 [ERROR] InnoDB: Upgrade after a crash is not supported. The redo log was created with MariaDB 10.4.12.
2020-09-20 8:28:02 0 [ERROR] InnoDB: Plugin initialization aborted with error Generic error
2020-09-20 8:28:02 0 [Note] InnoDB: Starting shutdown...
2020-09-20 8:28:02 0 [ERROR] Plugin 'InnoDB' init function returned error.
2020-09-20 8:28:02 0 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2020-09-20 8:28:02 0 [Note] Plugin 'FEEDBACK' is disabled.
2020-09-20 8:28:02 0 [ERROR] Unknown/unsupported storage engine: InnoDB
2020-09-20 8:28:02 0 [ERROR] Aborting
-Craig