How to hide designer error "The property xyz does not exist in the "http://schemas.microsoft.com/expression/blend/2008" namespace

Question

In VS 2015 (SP3) the designer shows an error for ignorable namespaces. In older versions (older SPs) this was not displayed as error.

The project compiles w/o errors and also in runtime there are no errors. So only the designer shows this as error.

How to remove this error from the Error List?

Hey and don't say the Visibilty property does not exist. I know this :-) and all things marked with the d prefix shall be ignored (mc:Ignorable="d"), but does not. Thanks for your Ideas.