Error msg "Exception: Could not load file or assembly 'DotNetOpenAuth.Core, Version=4.1.0.0, Culture=neutral"

I have already tested on locally and then upload to finish up hosting it can work. But about 4-5 hours after I come back the website and to Error msg "Exception: Could not load file or assembly 'DotNetOpenAuth.Core, Version=4.1.0.0, Culture=neutral" for more detail as below. Now I do not know what is the cause and I do not know how to fix it.

Pls help us in urgent issue
Thanks

Error msg
[quote]
Server Error in '/' Application.
Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.
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.Reflection.ReflectionTypeLoadException: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.

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.

Stack Trace:


[ReflectionTypeLoadException: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.]
   System.Reflection.RuntimeModule.GetTypes(RuntimeModule module) +0
   System.Reflection.RuntimeModule.GetTypes() +4
   System.Reflection.Assembly.GetTypes() +61
   Nop.Core.Plugins.PluginManager.Initialize() +1471

[Exception: Could not load file or assembly 'DotNetOpenAuth.Core, Version=4.1.0.0, Culture=neutral, PublicKeyToken=2780ccd10d57b246' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
Could not load file or assembly 'DotNetOpenAuth.Core, Version=4.1.0.0, Culture=neutral, PublicKeyToken=2780ccd10d57b246' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
]
   Nop.Core.Plugins.PluginManager.Initialize() +1795

[Exception: Could not load file or assembly 'DotNetOpenAuth.Core, Version=4.1.0.0, Culture=neutral, PublicKeyToken=2780ccd10d57b246' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
Could not load file or assembly 'DotNetOpenAuth.Core, Version=4.1.0.0, Culture=neutral, PublicKeyToken=2780ccd10d57b246' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.
]
   Nop.Core.Plugins.PluginManager.Initialize() +2187

[InvalidOperationException: The pre-application start initialization method Initialize on type Nop.Core.Plugins.PluginManager threw an exception with the following error message: Could not load file or assembly 'DotNetOpenAuth.Core, Version=4.1.0.0, Culture=neutral, PublicKeyToken=2780ccd10d57b246' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
Could not load file or assembly 'DotNetOpenAuth.Core, Version=4.1.0.0, Culture=neutral, PublicKeyToken=2780ccd10d57b246' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.
.]
   System.Web.Compilation.BuildManager.InvokePreStartInitMethodsCore(ICollection`1 methods, Func`1 setHostingEnvironmentCultures) +550
   System.Web.Compilation.BuildManager.InvokePreStartInitMethods(ICollection`1 methods) +132
   System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath) +90
   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): The pre-application start initialization method Initialize on type Nop.Core.Plugins.PluginManager threw an exception with the following error message: Could not load file or assembly 'DotNetOpenAuth.Core, Version=4.1.0.0, Culture=neutral, PublicKeyToken=2780ccd10d57b246' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
Could not load file or assembly 'DotNetOpenAuth.Core, Version=4.1.0.0, Culture=neutral, PublicKeyToken=2780ccd10d57b246' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.
.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +9850940
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +101
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +254


Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.17626 [/quote]

chomayanh wrote:

It could mean the DLL is broken when uploading. Try deleting all the related DLLs, re-upload, and reload your plugins (Reload Plugin List). :)

wooncherk wrote:

Do you mean I delete the "Plugins" folder of Hosting and reupload it? Sorry for idiot question
Thanks

chomayanh wrote:

It depends. It seems like you are having issue with DotNetOpenAuth.Core, which is part of 'ExternalAuth.OpenId' plugin. So you just need to delete this particular folder (ExternalAuth.OpenId) and re-upload it. :D

wooncherk wrote:

I do del 2 folders "ExternalAuth.OpenId" & "ExternalAuth.Facebook" and try to re-upload. It works! Amazing
So, which causes this error to occur?
Thanks

chomayanh wrote:

As explained, it's due to the broken DLL files when uploading through FTP. :D

wooncherk wrote:

Thanks in advance!

No problem. :D