Hi all,

I'm getting the following error when trying to upload media images in the back office:

{
  "Message": "An error has occurred.",
  "ExceptionMessage": "Object reference not set to an instance of an object.",
  "ExceptionType": "System.NullReferenceException",
  "StackTrace": "   at Umbraco.Web.WebApi.Filters.FileUploadCleanupFilterAttribute.OnActionExecuted(HttpActionExecutedContext actionExecutedContext)\r\n   at System.Web.Http.Filters.ActionFilterAttribute.CallOnActionExecuted(HttpActionContext actionContext, HttpResponseMessage response, Exception exception)\r\n   at System.Web.Http.Filters.ActionFilterAttribute.<>c__DisplayClass2.<System.Web.Http.Filters.IActionFilter.ExecuteActionFilterAsync>b__1(CatchInfo`1 info)\r\n   at System.Threading.Tasks.TaskHelpersExtensions.<>c__DisplayClass4`1.<Catch>b__3()\r\n   at System.Threading.Tasks.TaskHelpersExtensions.<>c__DisplayClass9`1.<CatchImplContinuation>b__8(Object state)"
}

This is the response given when a call is made to this URL:

/umbraco/backoffice/UmbracoApi/Media/PostAddFile?origin=blueimp

It only occurs on a development server. I cannot replicate it locally. The site is running on Umbraco 7.2.6, .NET 4.5.2, and IIS 8. It was recently upgraded from Umbraco 6.2.4 and .NET 4.

Any help is appreciated. Let me know if more info is required.

Thanks.

Steven.