How To Fix RU603 - User interface predefined, because there is no definition in Customizing

RU603 - Overview

• Message type: E = Error

• Message class: RU - Messages for order completion confirmation

• Message number: 603

• Message text: User interface predefined, because there is no definition in Customizing

What causes this issue?

A profile for single screen entry has not been defined as a standard
profile, neither has the current user been assigned a profile in the
CORUPROF parameter in the user defaults.

System Response

For single screen entry, the system uses a firmly defined interface.

How to fix this error?

If you do not want to use this firmly defined interface for entering
data, you have the following options:
Define a profile for single screen entry as a standard profile.
<DS:TRAN.OPK0>Execute function</>
Assign a profile for single screen entry to the CORUPROF parameter in
the user defaults for the current user.
<DS:TRAN.SU3>Execute function</>

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.

RU603 - Details

• The SAP error message RU603 indicates that there is a problem with the user interface configuration in the SAP system. Specifically, it means that the system is trying to access a predefined user interface that does not have a corresponding definition in the Customizing settings. This can occur in various scenarios, such as when a user tries to access a transaction or a report that relies on a specific user interface configuration that hasn't been set up correctly.
  
  Cause:
  
  Missing Customizing Entries: The most common cause is that the necessary entries for the user interface are missing in the Customizing settings. This could be due to incomplete configuration or changes that were not properly implemented.
  Transport Issues: If the configuration was transported from one system to another (e.g., from development to production), there may have been issues during the transport process that resulted in missing definitions.
  Version Mismatch: Sometimes, the error can occur if