How To Fix DPR_TASK021 - You cannot create a subtask for task &1

DPR_TASK021 - Overview

• Message type: E = Error

• Message class: DPR_TASK - Messages for Tasks

• Message number: 021

• Message text: You cannot create a subtask for task &1

What causes this issue?

Possible causes:
The project type does not allow a task hierarchy (see Customizing for
<LS>Project Management</> under <LS>Define Project Types</>).
You have selected <LS>With Summary Tasks</> for the task hierarchy in
the project type and one of the following points applies:
You have already entered data relevant to the execution of the task
(e.g. planned work)
You have assigned roles
You have entered qualifications

System Response

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

How to fix this error?

If you selected a project type that allows summary tasks, choose one of
the following options:
Create a new task at the same level and move the existing task to the
new task.
Delete the execution-relevant data from the task, and delete the role
and qualification assignments. Then create a subtask.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message DPR_TASK021 - You cannot create a subtask for task &1 ?

  The SAP error message DPR_TASK021, which states "You cannot create a subtask for task &1," typically occurs in the context of project management within the SAP system, particularly when using the SAP Project System (PS) or SAP Portfolio and Project Management (PPM) modules. This error indicates that the task you are trying to create a subtask for does not meet certain criteria or conditions.
  Causes:
  
  
  Task Type Restrictions: The task you are trying to create a subtask for may not be of a type that allows for subtasks. For example, certain predefined task types may not support the creation of subtasks.
  
  
  Task Status: The status of the parent task may not allow for the creation of subtasks. For instance, if the task is completed or closed, you may not be able to add subtasks.
  
  
  Hierarchy Limitations: There may be restrictions on the hierarchy level of tasks. Some configurations may limit how many levels of