SAP Message AO261 - Project definition &2 is being processed by user &1

Diagnosis
Project definition &V2& is blocked by user &V1&. Therefore,appropriation request &V2&, which belongs to project definition &V2&,cannot be processed now.

System Response
The system does not allow processing of the appropriation request, andthe project definition belonging to it, at the same time.

Procedure
Wait until user &V1& has finished.