SAP Message RSDD303 - Maintenance of aggregate &3 not possible due to block by user &1

Diagnosis
For the maintenance of aggregate &V3& for InfoCube &V2& the aggregatemust be locked. The aggregate is however, already blocked by anothertransaction from user &V1&.
With the other transaction, you can also be dealing with themaintenance of aggregate &V3&, the creation of this aggregate or theuse of the aggregate for the creation of another one.

System Response
The maintenance of aggregate &V3& is not possible at the moment.

Procedure
Check why the aggregate &V3& is locked by user &V1& and then call themaintenance up again.