Enterprise Library and custom Exception Handler

If you are using the Microsoft Enterprise Library, trying to implement IExceptionHandler, and your custom exception handler is not firing, then this post is for you.

Check the following things:
1 - Make sure your IExceptionHandler class is prefixed by the attribute [ConfigurationElementType(typeof(CustomHandlerData))]

2 - Make sure your IException Handler class has not only a public constructor, but a public constructor that accepts a NameValueCollection argument. I.e.

public MyHandlerClass(NameValueCollection collection) {}

3 - Are you calling ExceptionPolicy.HandleException(exc, "YourExceptionPolicyName") ? If not, add that to where you catch exceptions globally, such as Global.asax's Application_Error in a web application.

4 - Check your web.config setup. The add node has a type="X, Y" property where X is the name of your class and Y is the assembly.

  <exceptionHandling>
    <exceptionPolicies>
      <add name="My Exception Policy">
        <exceptionTypes>
          <add name="All Exceptions" type="System.Exception, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
            postHandlingAction="None">
            <exceptionHandlers>
              <add type="CustomExceptionHandler, MyAssemblyThatContainsHandler, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"
                name="CustomExceptionHandler" />
            </exceptionHandlers>
          </add>
        </exceptionTypes>
      </add>
    </exceptionPolicies>
  </exceptionHandling>