I created a new space and attempted to rename its "Home" page to "Übersicht". The page is not displayed after renaming, a page not found page is displayed instead. The same error message is displayed when clicking on the space name in the "Your spaces" list.

I think this is critical since it makes the space inaccessible.

The "Übersicht" page is however properly shown when clicking in the corresponding entry in the "Recently Updated" list. Also other places that show this link (nav trails, content tree) work correctly.