Error when executing "create pfile from spfile" I just installed Oracle database 12cR2 and am trying to startup a database. 

I am trying to create a pfile from spfile using following query.

create pfile from spfile;


Then I get the following errors.

create pfile from spfile
*
ERROR at line 1:
ORA-01565: error in identifying file '?=/dbs/spfile@.ora'
ORA-27077: too many files open


Can anybody tell me what's going on here or what I am doing wrong?
ORA-27077: too many files open


Based on that error I guess you have reached the limit of maximum open files.

You can check the soft and hard limits with ulimit -Sn and ulimit -Hn. Configure it in /etc/security/limits.conf or a seperate file under /etc/security/limits.d/. Check the list of actual open files with lsof -u oracle (if the user running the instance is oracle).