I wrote about implementing a custom profile provider inside of your ASP.NET MVC application yesterday. If you haven’t read the article, don’t sweat it.  Most of the stuff I write is rubbish anyway.

Since you have joined me today, though, I might as well offer up a little tip: you can run into trouble, like I did, if you enable your custom profile provider inside of an application which is deployed using a Web Deployment Project.  Everything will run great on your local machine and you’ll probably take an early lunch because you got the code running in no time flat and the build server is happy and all tests pass and, gosh, maybe you’ll just cut out early because it is Friday after all.  But then the first user hits the integration machine and, that’s right, yellow screen of death. Lucky you, just as you’re walking out the door, the user kindly sends the exception message and stack trace:

Value cannot be null. Parameter name: type Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Stack Trace:
[ArgumentNullException: Value cannot be null. Parameter name: type] System.Activator.CreateInstance(Type type, Boolean nonPublic) +2796915 System.Web.Profile.ProfileBase.CreateMyInstance(String username, Boolean isAuthenticated) +76 System.Web.Profile.ProfileBase.Create(String username, Boolean isAuthenticated) +312

User error?  Not this time. Damn!

One hour later… you notice the harmless “Treat as library component (remove the App_Code.compiled file)” setting on the Output Assemblies Tab of your Web Deployment Project.

You have no idea why, but you uncheck it.  You test and everything works great both locally and on the integration machine.  Application users think you’re the best and you’re still going to catch the last half hour of happy hour.  Happy Friday.