In this post, you’ll learn more about the Oracle ErrorORA-12336: cannot login to database (link name string) with the details on why you receive this error and the possible solution to fix it.
Oracle Error Description
ORA-12336: cannot login to database (link name string)
Reason for the Error ORA-12336: cannot login to database (link name string)
You are tyring to login while another user is mounting or dismounting the same database.
How to fix the Error ORA-12336: cannot login to database (link name string) ?
You can fix this error in Oracle by following the below steps
Check to see if the database is in the middle of being mounted or opened and try your login again once the database is accessible.