How to fix the Oracle error ORA-19957: database should have no datafiles in unknown state?

In this post, you’ll learn more about the Oracle ErrorORA-19957: database should have no datafiles in unknown state with the details on why you receive this error and the possible solution to fix it.

Oracle Error Description

ORA-19957: database should have no datafiles in unknown state

Reason for the Error ORA-19957: database should have no datafiles in unknown state

The operation failed because the database had one or more datafiles that were in an unknown state.

How to fix the Error ORA-19957: database should have no datafiles in unknown state ?

You can fix this error in Oracle by following the below steps

Drop the datafiles or recover them and bring them online.