Internal error: Unknown exception occurred

What causes this issue?

An internal program error occurred.

System Response

The selected processing step cannot be executed.

How to fix this error?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Procedure for System Administrators

Contact SAP by creating an OSS message. Inform SAP of the message
number for this message and provide the following information:
Program: &V1&
Include: &V2&
Line: &V3&

Error message extract from SAP system. Copyright SAP SE.