If I have a <tagMapping /> config file entry associated with a class in the App_Code folder, I seem to get the following error message without fail, at runtime:
Parser Error Message: The type 'MyNamespace.CustomDynamicValidator' is ambiguous: it could come from assembly 'C:\Windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\50512c51\4b64a02d\App_Code._ejsf967.DLL' or from assembly 'C:\WebApps\MyApp\ MyApp\bin\MyAssembly.DLL'. Please specify the assembly explicitly in the type name.
No biggie, just kind of a PITA actually. Now I need to put any code I'm using <tagMapping /> with in the root directory, and then it works fine.