أنشئ حسابًا أو سجّل الدخول للانضمام إلى مجتمعك المهني.
there is absolutely no way for doing that, because revit is a parametric design software, and with each new version , new parameters are being added, so if you were able to downgrade your file version t would be incompatible in some of it's feature, and that is the reason why you can' open it.
