Diagnosis
You have assigned a document type to the task in Customizing. However,the reclassification method is defined as a one-sided reclassification,which means that you only use a "source", but no "target".

System Response
The reclassification cannot be executed.

Procedure
Choose one option:

• If you want to post a one-sided reclassification, delete the document
type assignment from the task.

• If you want to post a normal reclassification, assign to the task a
method that uses a "target".