WBS Project does not have a parent.
WBS Project does not have a parent. A WBS project cannot exist without a parent.
Coding or data model propagation errors in an earlier version.
A WBS project without a parent cannot exist, and it cannot be used for any further processing.
What You Should Do
The WBS Project objects need to be removed.
Open a session.
Create a filter to bring in all WBS Projects. Use the Work Breakdown Structure tab on the filter dialog boxes.
Select each project in the Workspace Explorer and check if the parent object exists.
Delete all the projects that do not have a parent.