Troubleshooting IIS WCF Service Error Could not load file or assembly or one of its dependencies. An attempt was made to load a program with an incorrect format

Greetings!

In one of my Ax/Biztalk/Oracle integration projects, I had to write a web service to retrieve data from Oracle and as part of that development, I was using the Enterprise Library from Microsoft, On my development box, the build was good and my VS project compiles successfully without any issues.

However, while hosting the webservice on IIS 8.0 (Windows Server 2012)  and trying to browse from the internet explorer, I got this error below:

Error:

Server Error in '/' Application.

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Could not load file or assembly 'Framework.Data' 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 'Framework.Data' 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 'Framework.Data' 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 'Framework.Data' 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.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, RuntimeAssembly reqAssembly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) +210    System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean forIntrospection) +242    System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +17    System.Reflection.Assembly.Load(String assemblyString) +35    System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +122 [ConfigurationErrorsException: Could not load file or assembly 'Framework.Data' 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) +12480704    System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +499    System.Web.Configuration.AssemblyInfo.get_AssemblyInternal() +131    System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +331    System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath, Boolean& isRefAssemblyLoaded) +148    System.Web.Compilation.BuildManager.ExecutePreAppStart() +172    System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +1151 [HttpException (0x80004005): Could not load file or assembly 'Framework.Data' or one of its dependencies. An attempt was made to load a program with an incorrect format.]    System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +12601936    System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +159

Solution:

After some troubleshooting, found the fix is to set Enable 32-bit Application = True on the App Pool which is used by the webservice. This solved the problem.