How To Fix CN318 - External network number & cannot be used more than once

SAP Error Message - Details

• Message type: E = Error

• Message class: CN - Meldungen für Netzpläne

• Message number: 318

• Message text: External network number & cannot be used more than once

What causes this issue?

You were trying to create several networks with the same external
number &V1&.

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?

+nter an external number for each network so that the assignment of
subordinate objects is unique.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message CN318 - External network number & cannot be used more than once ?

  The SAP error message CN318, which states "External network number & cannot be used more than once," typically occurs in the context of project management or network planning within SAP. This error indicates that the external network number you are trying to use has already been assigned to another network or project, and SAP does not allow the same external network number to be reused.
  Cause:
  
  Duplicate External Network Number: The primary cause of this error is that the external network number you are trying to assign is already in use by another network or project.
  Data Entry Error: It may also occur due to a simple data entry mistake where the same number is inadvertently entered multiple times.
  Configuration Issues: In some cases, configuration settings in the project system may lead to this error if the system is not set up to handle external network numbers correctly.
  
  Solution:
  
  Check Existing Networks: Verify if the external network number you are trying to use is already assigned to another network. You can do this by checking the network overview or using transaction codes like CN21 (Create Network) or CN22 (Change Network).
  Use a Unique Number: If the external network number is indeed in use, you will need to select a different, unique external network number for your current project or network.
  Review Configuration: If you believe this is an error in the system configuration, consult with your SAP Basis or project system administrator to ensure that the settings for external network numbers are correctly configured.
  Data Cleanup: If there are orphaned or incorrectly assigned external network numbers in the system, consider cleaning up the data to avoid conflicts.
  
  Related Information:
  
  Transaction Codes: Familiarize yourself with relevant transaction codes such as CN21 (Create Network), CN22 (Change Network), and CN41 (Display Network) to manage networks effectively.
  SAP Notes: Check SAP Notes for any known issues or patches related to this error message. SAP Notes can provide additional insights or solutions that may not be covered in standard documentation.
  Documentation: Review SAP documentation related to project systems and network management for best practices on managing external network numbers.
  
  If the issue persists after following these steps, it may be beneficial to consult with your SAP support team or reach out to SAP support for further assistance.