How To Fix /CUM/MSG423 - The entry & is not a valid external number for this design type

/CUM/MSG423 - Overview

• Message type: E = Error

• Message class: /CUM/MSG -

• Message number: 423

• Message text: The entry & is not a valid external number for this design type

Self-Explanatory Message

Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.

To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.

Unfortunately, there isn't any extra information in this error notice.

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/CUM/MSG423 - Details

• The SAP error message /CUM/MSG423 The entry & is not a valid external number for this design type typically occurs in the context of SAP's Classification and Variant Configuration (CVC) functionalities. This error indicates that the system is unable to recognize the external number (which could be a material number, configuration number, or similar identifier) that you are trying to use for a specific design type.
  Causes:
  
  Invalid External Number: The external number you are trying to use does not exist in the system or is not valid for the specified design type.
  Incorrect Configuration: The design type may not be correctly configured to accept the external number you are providing.
  Data Inconsistency: There may be inconsistencies in the master data or classification data that prevent the system from recognizing the external number.
  Authorization Issues: The user may not have the necessary authorizations to access the data related to the external number.
  
  Solutions:
  
  Verify the External Number: