How To Fix CN870 - Choose another key for alternative; this one already exists

SAP Error Message - Details

• Message type: E = Error

• Message class: CN - Meldungen für Netzpläne

• Message number: 870

• Message text: Choose another key for alternative; this one already exists

What causes this issue?

The alternative you have entered for the standard network already
exists. Either the standard network is:
marked for deletion or
in a validity area, that does not agree with the key date.

System Response

INCLUDE 'NA_ALLG_NOVERARBEITUNG' OBJECT DOKU ID TX

How to fix this error?

Enter a different key for the alternative.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message CN870 - Choose another key for alternative; this one already exists ?

  The SAP error message CN870 ("Choose another key for alternative; this one already exists") typically occurs in the context of project management or when working with alternative items in SAP. This error indicates that you are trying to create or assign an alternative key (such as a project number, WBS element, or other identifiers) that already exists in the system.
  Cause:
  
  Duplicate Key: The primary cause of this error is that the key you are trying to use has already been assigned to another object in the system.
  Data Entry Error: It may also occur due to a simple data entry mistake where the same key is inadvertently entered multiple times.
  System Configuration: In some cases, the system configuration may not allow for certain keys to be reused or may have restrictions on key formats.
  
  Solution:
  
  Check Existing Keys: Before creating a new alternative key, check the existing keys in the system to ensure that the key you want to use is not already in use. You can do this by searching for the key in the relevant transaction or table.
  Use a Different Key: If the key is already in use, you will need to choose a different key that is unique and not currently assigned to any other object.
  Review Configuration: If you believe that the key should be available for reuse, review the configuration settings in your SAP system to see if there are any restrictions or settings that need to be adjusted.
  Consult Documentation: Refer to SAP documentation or help resources for specific guidelines on key management in your version of SAP.
  Contact Support: If you are unable to resolve the issue, consider reaching out to your SAP support team or consulting with an SAP expert for further assistance.
  
  Related Information:
  
  Transaction Codes: Depending on the context, you may be using transaction codes like CJ20N (Project Builder), CJ02 (Change Project), or others related to project management.
  SAP Notes: Check SAP Notes for any known issues or patches related to this error message.
  User Authorization: Ensure that you have the necessary authorizations to create or modify the keys in question.
  
  By following these steps, you should be able to resolve the CN870 error and successfully manage your project keys in SAP.