Deploy Mono MVC4 to AppHarbor

After upgrading to MonoDevelop 5,  (see my previous blog: Upgrading to MonoDevelop 5.1 in Linux Mint 16) you'll want to create an mvc4 app. But MD5 only comes with mvc3 templates. No problem. Chris F Carroll has published just the template you'll need. Clone this github project: Asp.Net MVC4 C# Razor Template for Mono on Mac and Linux

This template worked for me right out of the box. But when I deployed it to AppHarbor, it failed. The log shows this error:

error CS0234: The type or namespace name 'Mvc' does not exist in the namespace 'System.Web' (are you missing an assembly reference?)

I actually got the same error using the mvc3 templates that ship with MonoDevelop. This is due to some missing tags in the Web.config file. Find this section:

   <compilation debug="false" targetFramework="4.0">
      <assemblies>

You'll need to add these tags:

        <add assembly="System.Web.Helpers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.WebPages, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />

Now re-deploy your site. You'll find that these tags will disappear any time you modify your project references. I keep a copy inside a comment tag inside the web.config file, so I don't have to go looking for them every time I update my project.