In this post, you’ll learn more about the Oracle ErrorORA-12318: database (link name string) is already mounted with the details on why you receive this error and the possible solution to fix it.
Oracle Error Description
ORA-12318: database (link name string) is already mounted
Reason for the Error ORA-12318: database (link name string) is already mounted
You are attempting to mount a secondary database that has already been mounted by your instance.
How to fix the Error ORA-12318: database (link name string) is already mounted ?
You can fix this error in Oracle by following the below steps
to mount it. To establish access, use the ALTER DATABASE