How To Fix CN621 - Standard network contains no loops

SAP Error Message - Details

• Message type: E = Error

• Message class: CN - Meldungen für Netzpläne

• Message number: 621

• Message text: Standard network contains no loops

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message CN621 - Standard network contains no loops ?

  The SAP error message CN621 ("Standard network contains no loops") typically occurs in the context of project management and network planning within SAP, particularly when working with networks in the Project System (PS) module. This error indicates that the system expects a loop in the network structure, but it has not found one.
  Cause:
  
  Network Structure: The error usually arises when the network is defined in such a way that it does not allow for any loops. In project management, certain types of networks (like standard networks) are expected to have a specific structure that may include loops for certain calculations or processes.
  Incorrect Configuration: The network might be incorrectly configured, leading to a situation where the system cannot find a loop.
  Missing Relationships: There may be missing relationships or dependencies between activities in the network that would normally create a loop.
  
  Solution:
  
  Check Network Structure: Review the network structure to ensure that it is set up correctly. Look for any missing activities or relationships that should create a loop.
  Add Relationships: If the network is supposed to have loops, add the necessary relationships between activities to create them.
  Review Activity Types: Ensure that the activities in the network are of the correct type and that they are configured to allow for loops.
  Use Alternative Network Types: If loops are not required for your specific project, consider using a different type of network that does not require loops.
  Consult Documentation: Refer to SAP documentation or help resources for specific guidelines on network configuration and the requirements for loops.
  
  Related Information:
  
  Transaction Codes: You may need to use transaction codes like CN21 (Create Network) or CN22 (Change Network) to modify the network structure.
  SAP Notes: Check SAP Notes for any known issues or patches related to this error message.
  Training and Documentation: Consider reviewing SAP training materials or documentation related to Project System and network planning for best practices and guidelines.
  
  If the issue persists after trying the above solutions, it may be beneficial to consult with an SAP expert or your organization's SAP support team for further assistance.