WPF: The tag XXX does not exist in XML namespace ‘clr-namespace:YYY’

Posted on April 21, 2010 by ambilykk

When I used the custom WPF control in my project , I got the following compilation error

The tag ‘TestCtrl’ does not exist in XML namespace ‘clr-namespace:MceWpfContainer;assembly=MceWpfContainer’.

Following solution fixed my WPF custom control issue.
Solution:
1. Open the Project properties.
2. Change the target Framework from “.Net framework 4 Client profile” to “.Net framework 4”
3. Recompile the solution.

About ambilykk

I am a Technology Evangelist on Microsoft Technologies. I am carrying the passion on Microsoft technologies specifically on web technologies such as ASP .Net and Ajax. My interests also include Azure and Visual Studio. Technology adoption and learning is my key strength and technology sharing is my passion.

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3 Responses to WPF: The tag XXX does not exist in XML namespace ‘clr-namespace:YYY’

Ernesto Juarez says:

May 14, 2011 at 10:39 pm

Thanks a lot, I had the same problem and this solved it, it has been driving me crazy for a while. Funny thing is it was compiling without problems and I didn’t touch the tester at all just the user control library, what could have brought this problem?

Reply
Noman says:

July 18, 2011 at 9:18 pm

I had the same issue!! Thanks for the solution!!

Reply
Neko says:

November 10, 2015 at 1:44 pm

Wow, thanks for sharing this. This probably saved me a few hours.

Reply