I am trying to upgrade my site but is stuck. The progress bar says 0% and nothing happens when it runs for hours. When I look in the Windows Event log I see this:

Event code: 3005 
Event message: An unhandled exception has occurred. 
Event time: 8/13/2013 6:29:36 PM 
Event time (UTC): 8/13/2013 4:29:36 PM 
Event ID: 3f2d4b6f6070478d937c96634e1d4ddc 
Event sequence: 46 
Event occurrence: 1 
Event detail code: 0 
 
Application information: 
    Application domain: /LM/W3SVC/2/ROOT-2-130208849530555693 
    Trust level: Full 
    Application Virtual Path: / 
    Application Path: C:\websites\server-essentials.eu\ 
    Machine name: MJK-NOTEBOOK 
 
Process information: 
    Process ID: 8140 
    Process name: w3wp.exe 
    Account name: IIS APPPOOL\server-essentials.eu 
 
Exception information: 
    Exception type: HttpException 
    Exception message: Server cannot clear headers after HTTP headers have been sent.
   at System.Web.HttpResponse.ClearHeaders()
   at System.Web.Script.Services.RestHandler.WriteExceptionJsonString(HttpContext context, Exception ex, Int32 statusCode)
   at System.Web.Script.Services.RestHandler.ExecuteWebServiceCall(HttpContext context, WebServiceMethodData methodData)
   at System.Web.Handlers.ScriptModule.OnPostAcquireRequestState(Object sender, EventArgs eventArgs)
   at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

 
 
Request information: 
    Request URL: http://www.server-essentials.eu/Install/UpgradeWizard.aspx/RunUpgrade 
    Request path: /Install/UpgradeWizard.aspx/RunUpgrade 
    User host address: 127.0.0.1 
    User:  
    Is authenticated: False 
    Authentication Type:  
    Thread account name: IIS APPPOOL\server-essentials.eu 
 
Thread information: 
    Thread ID: 17 
    Thread account name: IIS APPPOOL\server-essentials.eu 
    Is impersonating: False 
    Stack trace:    at System.Web.HttpResponse.ClearHeaders()
   at System.Web.Script.Services.RestHandler.WriteExceptionJsonString(HttpContext context, Exception ex, Int32 statusCode)
   at System.Web.Script.Services.RestHandler.ExecuteWebServiceCall(HttpContext context, WebServiceMethodData methodData)
   at System.Web.Handlers.ScriptModule.OnPostAcquireRequestState(Object sender, EventArgs eventArgs)
   at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
 
 
Custom event details: 

I have disabled compression and output caching on IIS but that does not change anything. I have deleted the GettingStarted tab but I am not sure if that has anything to do with this issue. Does this have anything to do with cache settings in DNN?