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Editorial Team
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Asked: 2026-06-05T16:22:55+00:00

I am getting this error when I try to deploy my Web API project

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I am getting this error when I try to deploy my Web API project to both Cloud WebSites and Cloud Hosted Services on Azure:

"{"ExceptionType":"System.TypeLoadException","Message":"Could not load type 'System.ComponentModel.DataAnnotations.Schema.DatabaseGeneratedOption' from assembly 'System.ComponentModel.DataAnnotations, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.","StackTrace":"\r\nServer stack trace: \r\n   at System.Reflection.RuntimeAssembly.GetExportedTypes(RuntimeAssembly assembly, ObjectHandleOnStack retTypes)\r\n   at System.Reflection.RuntimeAssembly.GetExportedTypes()\r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerTypeResolver.GetControllerTypes(IAssembliesResolver assembliesResolver)\r\n   at System.Web.Http.WebHost.WebHostHttpControllerTypeResolver.GetControllerTypes(IAssembliesResolver assembliesResolver)\r\n   at System.Web.Http.Dispatcher.HttpControllerTypeCache.InitializeCache()\r\n   at System.Lazy`1.CreateValue()\r\n\r\nException rethrown at [0]: \r\n   at System.Reflection.RuntimeAssembly.GetExportedTypes(RuntimeAssembly assembly, ObjectHandleOnStack retTypes)\r\n   at System.Reflection.RuntimeAssembly.GetExportedTypes()\r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerTypeResolver.GetControllerTypes(IAssembliesResolver assembliesResolver)\r\n   at System.Web.Http.WebHost.WebHostHttpControllerTypeResolver.GetControllerTypes(IAssembliesResolver assembliesResolver)\r\n   at System.Web.Http.Dispatcher.HttpControllerTypeCache.InitializeCache()\r\n   at System.Lazy`1.CreateValue()\r\n   at System.Lazy`1.LazyInitValue()\r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerSelector.InitializeControllerInfoCache()\r\n   at System.Lazy`1.CreateValue()\r\n\r\nException rethrown at [1]: \r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerSelector.SelectController(HttpRequestMessage request)\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.SendAsyncInternal(HttpRequestMessage request, CancellationToken cancellationToken)\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)"}"

Here is just the message:

"Could not load type 'System.ComponentModel.DataAnnotations.Schema.DatabaseGeneratedOption' from assembly 'System.ComponentModel.DataAnnotations, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'."

It happens when I try to hit any of my API’s from the remote site. I know its not my 500 errors because some of my API’s wont throw them regardless of what happens.

One thing to note and I am not sure if this would affect anything is I started this project targeted at .NET 4.5 but then switched it to 4.0 when Azure Web Sites said they don’t support 4.5.

I can’t find anything about this except this link:
http://support.appharbor.com/discussions/problems/4822-internal-server-error-500-mvc-4-web-api

except that guy is using app-harbor, andeven still there is still no solution. Thanks of any help.

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1 Answer

  1. Editorial Team

    So it seemed that the problem was caused by me rolling back to .NET 4 from 4.5 and Entity not rolling back. It seems that Entity 5 only runs on .NET 4.5 and when the deployment was expecting 4.3.1 it had a 5.0.0 DLL and it messed everything up.

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