In this post, you’ll learn more about the Oracle ErrorORA-01531: a database already open by the instance with the details on why you receive this error and the possible solution to fix it.
Oracle Error Description
ORA-01531: a database already open by the instance
Reason for the Error ORA-01531: a database already open by the instance
During ALTER DATABASE, an attempt was made to open a database on an instance for which there is already an open database.
How to fix the Error ORA-01531: a database already open by the instance ?
You can fix this error in Oracle by following the below steps
If you wish to open a new database on the instance, first shutdown the instance and then startup the instance and retry the operation.