Question

Hello I have an ASP web application runs on C# as its backend that I’m trying to get running but the webpage (ran locally on my box) gives me the error message. Now the namespace the webapp is trying to reference is “using LAD.CDD.NSJ;” which are located in the App_Code folder.

The name of the files are Common.cs, Email.cs, Data.cs, and User.cs.

They all have a namespace call LAD.CDD.NSJ within the code. The previous programmers didn’t make those files into a dll and just kept it as a .cs file. I’m trying to use these files for another project but keep getting that error message.

Answer 1

The App_Code folder is a special folder in ASP.NET. ASP.NET will compile the types App_Code into an assembly which is actually separate from your web application assembly. This means, when you try and use those types from your backend code (e.g. an MVC controller), it is unable to resolve the type because those types will have a Build Action set to Content. With that build action, the file will not be included in the compilation of your main application.

What I would recommend doing, is ditch using App_Code because simply changing the build action to Compile won’t stop ASP.NET dynamically compiling an App_Code assembly, so you end up with ambiguous types (i.e., the runtime doesn’t know whether to use the type compiled into your main application assembly, or the dynamic App_Code assembly.

Move those files to another location, and set the Build Action (in Properties) to Compile.