ORA-12516: TNS:LISTENER COULD NOT FIND AVAILABLE HANDLER WITH MATCHING PROTOCOL STACK

1. ERROR : ORA-12516: TNS:listener could not find available handler with matching protocol stack
2. CAUSE : 進程到了最大值

   alter system set processes=300 scope=spfile;

   alter system set sessions=300 scope=spfile

重啓數據庫. 

SHUTDOWN IMMEDIATE

startup nomount

ALTER DATABASE MOUNT;
ALTER DATABASE OPEN;