Could not load file or assembly

Could not load file or assembly 'System.Web' or one of its dependencies. An attempt was made to load a program with an incorrect format.

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.

Exception Details: System.BadImageFormatException: Could not load file or assembly 'System.Web' or one of its dependencies. An attempt was made to load a program with an incorrect format.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Assembly Load Trace: The following information can be helpful to determine why the assembly 'System.Web' could not be loaded.

WRN: Assembly binding logging is turned OFF. To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1. Note: There is some performance penalty associated with assembly bind failure logging. To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].

Stack Trace:

[BadImageFormatException: Could not load file or assembly 'System.Web' or one of its dependencies. An attempt was made to load a program with an incorrect format.] System.Reflection.Assembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) +0 System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +495 System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +192 System.Reflection.Assembly.Load(String assemblyString) +42 System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +182 [ConfigurationErrorsException: Could not load file or assembly 'System.Web' or one of its dependencies. An attempt was made to load a program with an incorrect format.] System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +1259 System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +388 System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai) +145 System.Web.Configuration.AssemblyInfo.get_AssemblyInternal() +30 System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +227 System.Web.Compilation.WebDirectoryBatchCompiler..ctor(VirtualDirectory vdir) +204 System.Web.Compilation.BuildManager.BatchCompileWebDirectoryInternal(VirtualDirectory vdir, Boolean ignoreErrors) +57 System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) +257 System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) +413 System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) +125 System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean noAssert) +251 System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp, Boolean noAssert) +52 System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) +63 System.Web.HttpApplication.MapHttpHandler(HttpContext context, String requestType, VirtualPath path, String pathTranslated, Boolean useAppConfig) +574 System.Web.MapHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +183 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +277

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Version Information: Microsoft .NET Framework Version:2.0.50727.42; ASP.NET Version:2.0.50727.42 






Fixes
-  solution 1 : remove the System.Web.dll from the BIN directory . The refered dll is on 32 bits and the needed one is on 64 bits
- solution 2 : set the application compatibility on 32 bits( on asp.net or on windows forms)