How To Fix DPR_TASK020 - Cannot change external tasks: Action &1 is not possible

SAP Error Message - Details

• Message type: E = Error

• Message class: DPR_TASK - Messages for Tasks

• Message number: 020

• Message text: Cannot change external tasks: Action &1 is not possible

What causes this issue?

All tasks that are linked to the current task by a relationship must be
in change mode for action &V1&. However, at least one of these tasks
cannot be locked and therefore, cannot be imported for change. One
possible reason for this is that the task is already being edited.

System Response

The system does not perform action &V1&.

How to fix this error?

Repeat action &V1& once all the tasks linked to the current task by a
relationship can be imported for change.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message DPR_TASK020 - Cannot change external tasks: Action &1 is not possible ?

  The SAP error message DPR_TASK020 indicates that there is an issue with trying to change external tasks in the SAP Project Management module. The specific message states that the action you are attempting to perform (denoted by &1) is not possible for external tasks.
  Cause:
  This error typically occurs due to one of the following reasons:
  
  Task Type: The task you are trying to modify is an external task, which may have restrictions on certain actions (like changing status, deleting, or modifying attributes).
  Authorization Issues: The user may not have the necessary authorizations to perform the action on external tasks.
  Task Status: The current status of the task may not allow for the requested action (e.g., if the task is completed or locked).
  Project Settings: The project settings may restrict changes to external tasks based on configuration.
  
  Solution:
  To resolve the error, consider the following steps:
  
  Check Task Type: Verify that the task you are trying to change is indeed an external task and understand the limitations associated with it.
  Review Authorizations: Ensure that you have the necessary permissions to perform the action on the external task. You may need to consult with your SAP security team.
  Check Task Status: Look at the current status of the task. If it is in a state that does not allow changes (like completed or locked), you may need to change the status first or consult with a project manager.
  Consult Documentation: Review the SAP documentation or help files related to external tasks to understand what actions are permissible.
  Configuration Settings: If you have access, check the project configuration settings to see if there are any restrictions on external tasks that need to be adjusted.
  
  Related Information:
  
  SAP Notes: Check SAP Notes for any known issues or patches related to this error message.
  Transaction Codes: Familiarize yourself with relevant transaction codes such as CJ20N (Project Builder) or DPR (Project Management) to navigate and manage tasks effectively.
  User Forums: Consider visiting SAP community forums or user groups where similar issues may have been discussed, and solutions shared.
  
  If the issue persists after following these steps, it may be beneficial to reach out to your SAP support team for further assistance.