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

DPR_TASK020 - Overview

• 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.

DPR_TASK020 - Details

• 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