I’ve found it.
When a page, that is located inside an area, wants to access a controller that is located outside of this area (such as a shared layout page or a certain page inside a different area), the area of this controller needs to be added.
Since the common controller is not in a specific area but part of the main project, you have to leave area empty:
@Html.Action("MenuItems", "Common", new {area="" })
The above needs to be added to all of the actions and actionlinks since the layout page is shared throughout the various areas.
It’s exactly the same problem as here:
ASP.NET MVC Areas with shared layout
Edit: To be clear, this is marked as the answer because it was the answer for my problem. The above answers might solve the causes that trigger the same error.