MVC 4 Web Api Build in x64 mode giving error while executing "Could not load file or assembly 'xxx' or one of its dependencies - asp.net-mvc-4

Question

My MVC4 Web Api application is working fine when it is build in Any Cpu mode.In this mode it is creating 32 bit dll. However when I build the application in x64 mode then while executing it is giving following error:
Server Error in '/' Application.
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Could not load file or assembly 'CoreService' 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 'CoreService' 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 'CoreService' could not be loaded.
=== Pre-bind state information ===
LOG: User = xxx
LOG: DisplayName = CoreService
(Partial)
WRN: Partial binding information was supplied for an assembly:
WRN: Assembly Name: CoreService | Domain ID: 3
WRN: A partial bind occurs when only part of the assembly display name is provided.
WRN: This might result in the binder loading an incorrect assembly.
WRN: It is recommended to provide a fully specified textual identity for the assembly,
WRN: that consists of the simple name, version, culture, and public key token.
WRN: See whitepaper http://go.microsoft.com/fwlink/?LinkId=109270 for more information and common solutions to this issue.
LOG: Appbase = file:///D:/StartFromScratch/src/CoreService/
LOG: Initial PrivatePath = D:\StartFromScratch\src\CoreService\bin
Calling assembly : (Unknown).
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: D:\StartFromScratch\src\CoreService\web.config
LOG: Using host configuration file: C:\Users\310138409\Documents\IISExpress\config\aspnet.config
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/Temporary ASP.NET Files/root/a4e7fe2c/87c2ced5/CoreService.DLL.
LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/Temporary ASP.NET Files/root/a4e7fe2c/87c2ced5/CoreService/CoreService.DLL.
LOG: Attempting download of new URL file:///D:/StartFromScratch/src/CoreService/bin/CoreService.DLL.
ERR: Failed to complete setup of assembly (hr = 0x8007000b). Probing terminated.
Stack Trace:
[BadImageFormatException: Could not load file or assembly 'CoreService' or one of its dependencies. An attempt was made to load a program with an incorrect format.]
System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) +0
System.Reflection.RuntimeAssembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) +34
System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, RuntimeAssembly reqAssembly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) +152
System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean forIntrospection) +77
System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +16
System.Reflection.Assembly.Load(String assemblyString) +28
System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +38
[ConfigurationErrorsException: Could not load file or assembly 'CoreService' 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) +752
System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +218
System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai) +130
System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +170
System.Web.Compilation.BuildManager.GetPreStartInitMethodsFromReferencedAssemblies() +91
System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath) +258
System.Web.Compilation.BuildManager.ExecutePreAppStart() +135
System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +516
[HttpException (0x80004005): Could not load file or assembly 'CoreService' or one of its dependencies. An attempt was made to load a program with an incorrect format.]
System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +9874840
System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +101
System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +254
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Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.18055
I am not getting any concrete solution for the same. Moreover we cannot continue in 32 bit mode as It is making call to 64 bit unmanaged code. Thanks in advance.

Answer 1

Actually problem is because of IISExpress. It is 32bit of IISExpress is running whenever we are executing from VS2012 IDE so it is giving incorrect format error. So once I installed the IISexpress 8.0 and done the registry entry to make sure that IISExpress 64 bit get executed from VS2012; my problem got resolved.

Answer 2

You should properly configure your solution configurations for x64 build. Right click on your solution in VS, select Configuration Manager select x64 under Active solution platforms drop down list and check whether all of your projects has built with x64 platform.