ActivationManager Exception during build process?

Question

I\'m getting the following exception when building a website project in VS 2010:

The pre-application start initialization method Run on type WebActi         


        

Answer 1

In my case, I was seeing the message [AspNetCompiler] error ASPRUNTIME error message: Value cannot be null. in TeamCity.

In the full build logs, the more useful message at the bottom was:

error ASPRUNTIME : The pre-application start initialization method InitializePreStart on type MyApplication.MvcApplication threw an exception with the following error message: Value cannot be null.

As it turns out I had an exception being thrown by a method I had defined using PreApplicationStartMethod:

[assembly: System.Web.PreApplicationStartMethod(typeof(MyApp.MvcApplication), "InitializePreStart")]

namespace PrintFleet.PFE.RestService
{
    public class MvcApplication : System.Web.HttpApplication
    {
        //....
        public static void InitializePreStart()
        {
            // exception thrown here
        }
    }
}

The cause in my case was my prestart method was loading settings from the registry, and they didn't exist on the build server (but did on my machine, so it worked when I built it). I have no clue why webdeployment projects run this code.

I wrapped the entire thing in a try..catch that logs a fatal message (which in my app, goes to both the log file and windows event log). In builds, I don't really care if it fails since it doesn't need to do anything. In actual installations, if the settings are missing the app won't work (and so the log explains why).

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Now, to the OP the problem seems to be in web activator. I would not be surprised if there is a method using webactivor in App_Start folder that is throwing the error, which is making it look like it's coming from WebActivator. Check there first, wrap things in try..catch if needed. It's also possible there is a bug in webactivator itself.

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So because I came across this post while researching the problem, hopefully this information is useful to at least someone else.

TL;DR: Web deployment projects run the ApplicationPreStart methods when they compile. Ensure that you have try..catch blocks around any code run at prestart time or can otherwise handle the situation where the code is executed during compile time on your build server(s), outside of the IIS/hosting environment.