The tag "xxx" does not exist in XML namespace"yyy" / Reference could not be found

I have a winform usercontrol than I want to add to wpf project.

I added the relevant references (WindowsFormsIntegration, SystemWindowsForms and my user control dll) and added this row in my XAML:

xmlns:MyControl="clr-namespace:xx.xx.xx;assembly=xx.xx"

And then this:

<WindowsFormsHost><MyControl:control></MyControl:control></WindowsFormsHost>

When I write "MyControl:" the "control" is automated show up that mean VS recognize the control and all references added ok... but when I compile the project this give me the error in the title.

Edit

Its very strange when I'm compile the all project i've got error "The type or namespace name "xx' could not be found..." but I added all开发者_Python百科 the refernces and the VS recognize the namespace so why the compiler don't found them? If this problem will be solved I beleive the other problem also will disappear.

The solution is: Go to your project properties and change the Target Framework from Client Profile to the full version of the .Net you are using, see the image below. This problem happens if your DLL targets the full .NET Framework, and your WPF Application (main project) targets .Net Client Profile.

This happened to me when I included the assembly name in the namespace definition, but both controls were in the same assembly. Just removing the assembly part of the namespace declaration solved it.

Visual Studio will load the reference only for reflection so it will show correct intellisense correctly. But in order to compile, compiler will need all the dlls that your referenced dll is dependent on. So visual studio will show intellisense for mycontrol as it can find it in reference. But your myontrol may reference other dlls which you may not have added. You will have to add dependent references of mycontrol in your project too.

It could also be that the target framework is different between your projects. We host a class library dll with the WPF pages, and it was targeted to 'Any CPU', but the host application was targeted to 'x86'. Once they matched, the problem went away.

I ran into the same "The type or namespace name 'xx' could not be found..." issue.

It disappears when I moved my Visual Studio files on a local drive. They were stored on a shared network directory before. I dont know the root cause of this, but at least I can have my designer running now.

I've encountered this problem before and replacing <MyControl:control></MyControl:control> with just <MyControl:control/> fixed it for me.

No idea why though. It seems like the first form is only for controls which can contain other controls.