How to fix the Oracle error TNS-12623: TNS:operation is illegal in this state?

In this post, you’ll learn more about the Oracle ErrorTNS-12623: TNS:operation is illegal in this state with the details on why you receive this error and the possible solution to fix it.

Oracle Error Description

TNS-12623: TNS:operation is illegal in this state

Reason for the Error TNS-12623: TNS:operation is illegal in this state

Cause: Connection is half-duplex and a full-duplex operation was attempted.

How to fix the Error TNS-12623: TNS:operation is illegal in this state ?

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

Action: Not normally visible to the user. For further details, turn on tracing and reexecute the operation. If error persists, contact Oracle Customer Support.