I think this problem is due to some aggr

I think this problem is due to some aggregation that the cube have done on an attribute/hierarchy that is no more "activated" on the cube. I have processed my cube with 30% Optimization, set an X attribute to "Disabled" in my cube, than the problem occured. My attribute was'nt used by any calculation or anything. I was forced to add my X attribute back in my cube (but invisible, no optimization). Then no more problem! So : Try to add the X attribute named in the error back in your cube (or even back in the dimension if you need to). voilà!