How To Fix CN624 - Standard network contains loops and cannot be scheduled

SAP Error Message - Details

• Message type: E = Error

• Message class: CN - Meldungen für Netzpläne

• Message number: 624

• Message text: Standard network contains loops and cannot be scheduled

What causes this issue?

The standard network cannot be scheduled because the relationships to
activities have created a loop.

System Response

INCLUDE 'NA_ALLG_NOFUNKTION' OBJECT DOKU ID TX

How to fix this error?

RESET N1
Call up the network structure graphic.
Select the menu options <LS>Edit -> Functions -> Loop analysis ->
Execute</>.
The relationships causing the loop are highlighted.
Choose new relationships between activities so the loop no longer
exists.
Select the menu options <LS>Edit -> Functions -> Loop analysis ->
Execute</>.
The relationships are no longer highlighted.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message CN624 - Standard network contains loops and cannot be scheduled ?

  The SAP error message CN624 indicates that there are loops in the standard network of a project, which prevents the scheduling of the project. This error typically arises in the context of project management within SAP, particularly when using the Project System (PS) module.
  Cause:
  The primary cause of the CN624 error is the presence of circular dependencies in the network activities. This can happen due to:
  
  Incorrect Activity Relationships: Activities may be incorrectly linked, creating a situation where an activity depends on itself, either directly or indirectly.
  Missing or Incorrectly Defined Milestones: If milestones are not properly defined or linked, it can lead to circular dependencies.
  Manual Changes: Manual adjustments to the network structure that inadvertently create loops.
  
  Solution:
  To resolve the CN624 error, follow these steps:
  
  
  Check Activity Relationships:
  
  Go to the network in question and review the relationships between activities.
  Ensure that there are no circular dependencies. Each activity should have a clear predecessor and successor.
  
  
  
  Use the Network Overview:
  
  Utilize the network overview (transaction code CN21 or CN22) to visualize the network structure.
  Look for any activities that point back to themselves or create a loop.
  
  
  
  Adjust Relationships:
  
  If you find any incorrect relationships, adjust them to eliminate the loops.
  Ensure that the logical flow of the project is maintained.
  
  
  
  Check for Milestones:
  
  Verify that all milestones are correctly defined and do not create circular dependencies with the activities.
  
  
  
  Re-schedule the Network:
  
  After making the necessary adjustments, attempt to re-schedule the network using transaction code CN41 or CN42.
  
  
  
  Use the Scheduling Check:
  
  Use the scheduling check functionality to identify any remaining issues in the network.
  
  
  
  Related Information:
  
  Transaction Codes:
  
  CN21: Create Network
  CN22: Change Network
  CN41: Schedule Network
  CN42: Display Network
  
  
  Documentation: Refer to SAP Help documentation for detailed information on network planning and scheduling.
  Best Practices: Regularly review and validate network structures during project planning to avoid such issues.
  
  By following these steps, you should be able to identify and resolve the cause of the CN624 error, allowing you to successfully schedule your project network in SAP.