Good morning,
I have a big problem ...
I tried to install the upgrade to 2.6.09 but it returns me the error that you can see here:

www.apneateam.info/Default.apsx

=========================
Server Error in '/' Application.
Object reference not set to an instance of an object.
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.NullReferenceException: Object reference not set to an instance of an object.

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:


[NullReferenceException: Object reference not set to an instance of an object.]
   DotNetNuke.Entities.Tabs.TabController.GetTabByTabPath (Int32 portalId, tabPath String, String cultureCode) +18
   DotNetNuke.HttpModules.UrlRewriteModule.RewriteUrl (HttpApplication app, String & portalAlias) +3140
   DotNetNuke.HttpModules.UrlRewriteModule.OnBeginRequest (Object s, EventArgs e) +961
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute () +141
   System.Web.HttpApplication.ExecuteStep (IExecutionStep step, Boolean & completedSynchronously) +69


Version Information: Microsoft .NET Framework Version: 4.0.30319; ASP.NET Version: 4.6.1087.0
===============================
I need to resolve quickly and I would be willing to pay the intervention of any of you.

Please help me.
Thank you

Ps. I ask for help because I am a graphic designer and do not absolutely know the DNN code.

my personal contact corrado@ursoleo.com