DNN Server - System.Runtime.InteropServices.COMException: The data is invalid

Question

One of our production servers running DNN (DotNetNuke) recently stopped working after being rebooted. All requests now give the following error:

[COMException (0x8007000d): The data is invalid. (Exception from HRESULT: 0x8007000D)]
   System.Runtime.InteropServices.Marshal.ThrowExceptionForHRInternal(Int32 errorCode, IntPtr errorInfo) +0
   System.Web.Handlers.AssemblyResourceLoader.EnsureHandlerExistenceChecked() +340
   System.Web.Handlers.AssemblyResourceLoader.IsValidWebResourceRequest(HttpContext context) +15
   System.Web.Security.FormsAuthenticationModule.OnEnter(Object source, EventArgs eventArgs) +300

   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +139
   System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +195
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +88

The machine is running Windows Server 2012/IIS8.5/ASP.NET 4.5.

I've searched for the error and seen suggestions that the web.config may have malformed XML, so I checked and it's fine, and hasn't changed in over a year.

I've also seen suggestions that we install the IIS URL Rewrite Module. I tried that and still no luck, and the site has been working for years without it installed.

The full web.config (minus connection strings) is here: pastebin.com/GpqB5H0U.

Here's the error in event viewer:

Or as text: pastebin.com/paUvF0he

Since the problems seemed to be triggered by a reboot I reverted the server to a backup from a week earlier, and it worked great until the next time it was rebooted, and the error appeared again. I checked and there haven't been any windows updates or changes to group policy that would have affected it.

Any ideas would be greatly appreciated.

Can you show the complete web.config and modules have installed on IIS? It is better to show the log in event viewer so that I can find the issue. When you reboot the server, did DNN start normally? — Bruce Zhang
The full web.config (minus connection strings) is here: pastebin.com/GpqB5H0U. — kevinlb
The stack-trace says that FormsAuthenticationModule is complaining. How do you have that configured in your project? I'm guessing a systemwide Windows Update to .NET Framework broke an assumption in DNN (DNN is ancient, anyway). — Dai
I think you should update to .NET Framework 4.8 before continuing any other line of investigation - I'm willing to bet a dollar or two that the issue is related to the SameSite cookie patch Microsoft shipped to .NET Framework this year. — Dai

kevinlb kevinlb · Accepted Answer · 2020-12-04T22:34:36

So I finally fixed it and I'll post the solution here on the off chance it helps someone else, though I suspect it was something unique to our setup.

@dai's comments led me to look at webresource.axd since it was in a comment in the EnsureHandlerExistenceChecked() method, and I discovered that somehow a folder called webresource.axd with its own web.config file had been created in the website's root folder. It didn't serve any purpose that I could see so I deleted the folder and its contents and suddenly everything started working.

Thanks everyone who responded. @dai do you want to post your comments as an answer so I can give you credit for finding the solution?

DNN Server - System.Runtime.InteropServices.COMException: The data is invalid

1 Answers