Selected email template &1 is not valid for output type &2.

What causes this issue?

The selected email template is not valid for the selected output type.

System Response

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

How to fix this error?

Chose a different output type or assign the selected email template in
activity "Assign Email Templates" to the output type of the application.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.