Hi, I am migrating a web platform from another hoster (Azure VMs) into my own Azure VM and when I navigate to a certain area of the site I am getting an error. In the TraceLog it shows:

2020-01-31 11:46:46,125 [P3516/D2/T19] ERROR 

Umbraco.Core.UmbracoApplicationBase - An unhandled exception occurred
System.Security.SecurityException: An attempt to download a remote file has been halted because the file is larger than allowed.
   at ImageProcessor.Web.Helpers.RemoteFile.<GetWebResponseAsync>d__17.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at ImageProcessor.Web.Services.CloudImageService.<GetImage>d__16.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at ImageProcessor.Web.HttpModules.ImageProcessingModule.<ProcessImageAsync>d__34.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.TaskAsyncHelper.EndTask(IAsyncResult ar)
   at System.Web.HttpApplication.AsyncEventExecutionStep.InvokeEndHandler(IAsyncResult ar)
   at System.Web.HttpApplication.AsyncEventExecutionStep.OnAsyncEventCompletion(IAsyncResult ar)
The Zone of the assembly that failed was:
MyComputer

So I had a look online and found some conversations related to the same issue here and here.

Looking in web.config I can see:

<httpRuntime requestValidationMode="2.0" enableVersionHeader="false" targetFramework="4.5" maxRequestLength="1048576" executionTimeout="360" fcnMode="Single" />

Also within web.config under system.Webserver:

<requestLimits maxAllowedContentLength="1073741824" maxUrl="65536" />

and in security.config:

<setting key="MaxBytes" value="8194304" />

So this seems like plenty in terms of max filesize to me (too much, in fact). I have the media folder set up in Azure blob storage and had a look in this to see if there were any files that exceeded 8MB. I can see some video files in there that are between 160-360MB and some images that are ~25MB. Obviously this is too large for the max specified size, but this is legacy code that has been sent over from a web agency so I am using the same settings as they set in the code which was working correctly.

So the live site currently uses those settings without issue whereas my site (not live yet until I can get it working properly), which uses the same config settings and source code comes up with that error. Does anyone know how I might diagnose the issue?

Thanks a lot,

John