"The located assembly's manifest definition does not match the assembly reference"

Question

I have deployed an .NET WebAPI app (compiled against .NET 4.5.2, and running locally) into an Azure App Service.

The error thrown there is

Could not load file or assembly 'System.Web.Mvc, Version=4.0.40804.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference.

I have checked that the System.Web.Mvc.dll in the App service's bin directory has a size of 505504 bytes - the very same size as my local System.Web.Mvc.dll, which is version 4.0.40804.0, changed 2014-09-25, and working locally without issue. The only difference I can tell is that I have .NET 4.5.2 installed locally, not 4.6.1, like Azure does.

The entry in my Web.config is

  <dependentAssembly>     <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />     <bindingRedirect oldVersion="1.0.0.0-5.0.0.0" newVersion="4.0.40804.0" />   </dependentAssembly> 

but I have already tried

  <dependentAssembly>     <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />     <bindingRedirect oldVersion="1.0.0.0-5.0.0.0" newVersion="4.0.0.0" />   </dependentAssembly> 

which doesn't work either.

How do I have to edit that entry for my application to find the System.Web.Mvc.dll?

For reference, the full error message is:

Server Error in '/' Application.

Could not load file or assembly 'System.Web.Mvc' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

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.IO.FileLoadException: Could not load file or assembly 'System.Web.Mvc' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

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.Mvc' 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:

[FileLoadException: Could not load file or assembly 'System.Web.Mvc' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)]

[FileLoadException: Could not load file or assembly 'System.Web.Mvc, Version=4.0.40804.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)] 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) +36 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) +21 System.Reflection.Assembly.Load(String assemblyString) +28 System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +38

[ConfigurationErrorsException: Could not load file or assembly 'System.Web.Mvc, Version=4.0.40804.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)] System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +738 System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +217 System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai) +130 System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +170 System.Web.Compilation.BuildManager.GetPreStartInitMethodsFromReferencedAssemblies() +92 System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath, Boolean& isRefAssemblyLoaded) +290 System.Web.Compilation.BuildManager.ExecutePreAppStart() +157 System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +531

[HttpException (0x80004005): Could not load file or assembly 'System.Web.Mvc, Version=4.0.40804.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)] System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +9947380 System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +101 System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +261

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.6.1055.0

Answer 1

You may check "assembly versions" in Tools > Nuget Package Manager > Manage NuGet Packages for Solution (VS2015). Check versions of assemblies used in your projects in solution & use single version.