I have created a custom Button with some extra properties. I want to register it in my Application Page like this

<%@ Register Namespace="Test1.Test2.Helpers" Assembly="Test1.Test2" TagPrefix="test" %>

But it casts an exception and saying something like it cannot find the assembly.


1 Answer 1


You need to deploy the assembly to GAC and use the fully qualified Name in assembly tag as:

<%@ Register Tagprefix="MyControls" 
    Assembly="KM.MyControls, Version=, Culture=neutral, PublicKeyToken=<Your token>" %>

Then you can reference your User Control

   <MyControls:MyUserControl runat="server"/>
  • It is same assembly which contains the application page so it must be GAC:ed ? and I just added a useul class which inherits from Button class
    – Medes
    Sep 22, 2014 at 15:57
  • add the "Test1.Test2" assembly to GAC.
    – Aanchal
    Sep 22, 2014 at 15:59
  • It is not User Control, It is a normal class which is derived from Button and it is in the same project that contains the Application Page (SharePoint Project) which is already GAC:ed
    – Medes
    Sep 23, 2014 at 7:59
  • So just add fully qualified name to your assembly tag.
    – Aanchal
    Sep 23, 2014 at 8:02

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