Thanks for explaining again, I agree with you again, since this is another kind of stall due to pressure loss the revers (wrong) way. I thought a wing (blade) stall also had something to do with this, but that may be minor or not at all. But if that is the case, I guess it only can happen to axial compressors. (like stalling a ducted fan because of too high rpm caused by a too big engine than what the impeller blade angle is made for.)