Can't assign UWidgetBlueprint to WidgetComponent

Hello, please help me to clear this out, I can’t really get why this is happening( It says UWidgetBlueprint(which is inherited from UUserwidget as it says in editor), can’t be assigned to widget component -> widget class. I also tried to find UUserwidget instead of UWidgetBlueprint but in that way it can’t be found! I can assign it manualy by the way so types are all right.

I tried to cast from this UWidgetBlueprint to UUserWidget - cast failed. As I see in UWidgetBlueprint doc page it’s has no UUserWidget in hieracy. So why then I can setup it manualy in editor by dragging to the UUserWidget!? And how should I do it in code? Please, anyone…