The DevExpress ASPxScheduler control is a nice calendar control. It seems to take a fair amount of code and study to get all the bits of code together you need to use it, but once it's together it presents a really nice interface to the user.
The control allows full customization of the appointment display. On the page that holds the calendar, you define, for example, a "VerticalAppointmentTemplate" item for the daily view, and give it the name of a user control you've defined in order to display an appointment in that particular view. Then the user has the ability to drag the appointment around and do other clever things with it for rescheduling, etc, and the calendar control handles the placement of your user control at the correct time on the calendar in the web page. Pretty nice!
So I set up my controls the way I wanted them, tested to make sure it worked, checked the code in, and sent it to QA to look at. Response: "The page errors out as soon as we navigate to it."
Further investigation revealed that an exception was being thrown, with the message "The file 'MyVerticalAppointment.ascx.cs' does not exist". For some reason, it wanted the source code for my user control, and I had no idea why. Like all of our other codebehinds, the code is compiled into an assembly that is published on the web site. No source code is put out there.
If you're an ASP.Net veteran from way back, this is probably throwing up all kinds of red flags for you, but I'm not. Googling for various terms in the exception didn't really turn up much, except that most of the similar solutions seemed to involve converting the file or the application to a web application, something I vaguely remember from around the time we upgraded to VS2005, but never really had to deal with. Besides, I knew that our application was already set up the way we needed it. There was no conversion to be done as far as I could tell.
So after futzing around with it for a while, my coworker pointed out an oddity in the user control. Instead of using a CodeBehind declaration to point to the code, it was using a CodeFile declaration.
That was the problem, of course. It wasn't that I had converted from a Web Application to Web Project or back again, it was simply that I had borrowed a piece of sample code from a DevExpress project that was using a CodeFile declaration, inappropriately for my project. Switched it to CodeBehind, didn't even have to recompile, and everything worked properly.
If it's useful, here's the stack trace of the exception that was thrown:
at System.Web.UI.TemplateParser.ProcessException(Exception ex) at System.Web.UI.TemplateParser.ParseStringInternal(String text, Encoding fileEncoding) at System.Web.UI.TemplateParser.ParseString(String text, VirtualPath virtualPath, Encoding fileEncoding) at System.Web.UI.TemplateParser.ParseFile(String physicalPath, VirtualPath virtualPath) at System.Web.UI.TemplateParser.ParseInternal() at System.Web.UI.TemplateParser.Parse() at System.Web.Compilation.BaseTemplateBuildProvider.get_CodeCompilerType() at System.Web.Compilation.BuildProvider.GetCompilerTypeFromBuildProvider(BuildProvider buildProvider) at System.Web.Compilation.BuildProvidersCompiler.ProcessBuildProviders() at System.Web.Compilation.BuildProvidersCompiler.PerformBuild() at System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean noAssert) at System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp, Boolean noAssert) at System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) at System.Web.UI.PageHandlerFactory.System.Web.IHttpHandlerFactory2.GetHandler(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) at System.Web.HttpApplication.MapHttpHandler(HttpContext context, String requestType, VirtualPath path, String pathTranslated, Boolean useAppConfig) at System.Web.HttpApplication.MapHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)