System.Web.HttpParseException: Could not load the assembly App_Web_xxxx. Make sure that it is compiled before accessing the page.

I always received error message from the web application after the last deployment.

System.Web.HttpParseException: Could not load the assembly 'App_Web_fsfkjwna'. Make sure that it is compiled before accessing the page. ---> System.Web.HttpParseException: Could not load the assembly 'App_Web_fsfkjwna'. Make sure that it is compiled before accessing the page. ---> System.Web.HttpParseException: Could not load the assembly 'App_Web_fsfkjwna'. Make sure that it is compiled before accessing the page. ---> System.Web.HttpException: Could not load the assembly 'App_Web_fsfkjwna'. Make sure that it is compiled before accessing the page.at System.Web.UI.TemplateParser.GetType(String typeName, Boolean ignoreCase, Boolean throwOnError)at System.Web.UI.TemplateParser.ProcessInheritsAttribute(String baseTypeName, String codeFileBaseTypeName, String src, Assembly assembly)at System.Web.UI.TemplateParser.PostProcessMainDirectiveAttributes(IDictionary parseData)--- End of inner exception stack trace ---at System.Web.UI.TemplateParser.ProcessException(Exception ex)at System.Web.UI.TemplateParser.PostProcessMainDirectiveAttributes(IDictionary parseData)at System.Web.UI.PageParser.PostProcessMainDirectiveAttributes(IDictionary parseData)at System.Web.UI.TemplateParser.ProcessMainDirective(IDictionary mainDirective)at System.Web.UI.TemplateControlParser.ProcessMainDirective(IDictionary mainDirective)at System.Web.UI.PageParser.ProcessMainDirective(IDictionary mainDirective)at System.Web.UI.TemplateParser.ProcessDirective(String directiveName, IDictionary directive)at System.Web.UI.BaseTemplateParser.ProcessDirective(String directiveName, IDictionary directive)at System.Web.UI.TemplateControlParser.ProcessDirective(String directiveName, IDictionary directive)at System.Web.UI.PageParser.ProcessDirective(String directiveName, IDictionary directive)at System.Web.UI.TemplateParser.ParseStringInternal(String text, Encoding fileEncoding)--- End of inner exception stack trace ---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)--- End of inner exception stack trace ---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)

After struggling for a while, i found that by doing 2 steps can solve this problem.

1. Create a new Application Pool.


2. Change the application pool for my application to the newly created pool.
   

Create new Application Pool in Internet Information Server 6 (Windows Server 2003)

Open IIS 6

Right click on Application Pools node from the tree view

Select New -> Application Pool ... from the context menu

Enter Application pool ID (myAppPool) and click OK.

New Application Pool Created.

Change the application pool for my application to the newly created pool.

Open IIS

From the explorer view, open the Web Sites folder.

Point to the web application that want to change the Application Pool (mysite.com)

Right click on mysite.com

Select Properties

A new Properties window pop up, Select "Home Directory" tab

Change the Application Pool to "myAppPool" and click OK.

Application Pool Changed

Done.

For Windows XP developer, when face this error, Kill aspnet_wp.exe process,
go to C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files and delete all the temporary files. Try to compile your project again.