How To Fix CN839 - Start and target activities cannot be identical

CN839 - Overview

• Message type: E = Error

• Message class: CN - Meldungen für Netzpläne

• Message number: 839

• Message text: Start and target activities cannot be identical

What causes this issue?

You have entered the same activity number for both the beginning and
target activities.
When you include this standard network you would create a loop.

System Response

INCLUDE 'NA_ALLG_NOVERARBEITUNG' OBJECT DOKU ID TX

How to fix this error?

Enter a different activity number for the beginning and target
activities.

Error message extract from SAP system. Copyright SAP SE.

CN839 - Details

• The SAP error message CN839 ("Start and target activities cannot be identical") typically occurs in the context of project management or network planning within SAP, particularly when working with activities in a project or network. This error indicates that the system has detected an attempt to link an activity to itself, which is not allowed.
  
  Cause:
  The error arises when:
  
  You are trying to create a relationship (dependency) between an activity and itself. For example, if you attempt to set the predecessor and successor of an activity to be the same activity, SAP will throw this error.
  This can happen during the creation or modification of a project network or when defining relationships between tasks in a project.
  
  
  Solution:
  To resolve the CN839 error, you should:
  
  Check Activity Relationships: Review the relationships you are trying to establish. Ensure that you are not linking an activity to itself.
  Modify Relationships: If you find that an activity is incorrectly set