Error 2896 using a WiX C#/.NET 4 custom action

I am trying to use my first custom action in WiX and I get:

error 2896: Executing action CustomActionTest failed.

I am using Visual Studio 2010, WiX 3.5, 64-bit Windows 7 Ultimate, .NET Framework 4.

Here are what I think are the relevant sections:

<Binary Id="JudgeEditionCA" SourceFile="..\JudgeEditionCA\bin\Debug\JudgeEdition.CA.dll" />
<CustomAction Id="CustomActionTest" BinaryKey="J开发者_开发技巧udgeEditionCA" DllEntry="CustomActionOne" Execute="immediate"/>

<Control Id="Next" Type="PushButton" X="248" Y="243" Width="56" Height="17" Default="yes" Text="!(loc.WixUINext)" >
    <Publish Event="DoAction" Value="CustomActionTest">1</Publish>
    <Publish Event="DoAction" Value="InvalidClientDesc">CLIENT_DESC_VALID = "0"</Publish>
    <Publish Event="NewDialog" Value="VerifyReadyDlg">CLIENT_DESC_VALID = "1"</Publish>
</Control>

From the action:

namespace JudgeEditionCA
{
    public class CustomActions
    {
        [CustomAction]
        public static ActionResult CustomActionOne( Session session )
        {
            return ActionResult.Success;
        }
    }
}

And the configuration file from the custom action:

<configuration>
    <startup useLegacyV2RuntimeActivationPolicy="false">
        <supportedRuntime version="v4.0" />
    </startup>
</configuration>

And finally I have used a project reference in my WiX project to the custom action. I am not sure what I am doing wrong.

---

I figured it out by running my msi with the /lvx option to get a verbose logging. I also had to move my action to the InstallExecuteSequence section to get a meaningful error message. When the call to the CA was in the PushButton nothing meaningful was returned.

<InstallExecuteSequence>
    <Custom Action='CustomActionTest' After='InstallFinalize' />
</InstallExecuteSequence>

System.BadImageFormatException: Could not load file or assembly 'JudgeEdition' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded.

I changed the useLegacyV2RuntimeActivationPolicy attribute to true. Everything started working nicely.

<configuration>
    <startup useLegacyV2RuntimeActivationPolicy="true">
        <supportedRuntime version="v4.0" />
    </startup>
</configuration>

These links helped get me up to speed:

• What does 'useLegacyV2RuntimeActivationPolicy' do in the .NET 4 config?
• http://www.marklio.com/marklio/PermaLink,guid,ecc34c3c-be44-4422-86b7-900900e451f9.aspx

---

As a corollary to KnightsArmy's answer this error is also thrown when the DllEntry attribute on the CustomAction element is wrong. In my case I had a typo and the only error information I could get out of the log was the infamous error 2896.

---

I got the same error code but the root cause is because one of the Custom Action methods throws an exception. If you don't write try-catch and write meaningful error messages. The MSI log will just tell you the error#.

Cheers