Startup the database to determine at what phase does this error occur(nomount/ mount/open)
IF during nomount -env variables,kernel settings, init.ora
If during mount – permissions,env settings,corrupted files/filessystems
If during Open -recovery? who generated the trace file,
startup trigger problem(_system_trig_enabled=false)
corrupted online redo log, datafile (note 28814.1)
possible data dict corruption
You might have to open a support case with Oracle if it’s corruption related. or try setting some events to bypass it.