IIS error:

I noticed that my IT-shop web application does not work anymore after ugrade to 6.1 (it is not for sure that this error is related to upgrade but before upgrade IT shop worked). The error I get when I try to load IT-shop in web brower:

HTTP Error 500.19 - Internal Server Error
Absolute physical path "C:\inetpub\custerr" is not allowed in system.webServer/httpErrors section in web.config file.  Use relative path instead.

In IIS I have checked configuration of Error pages for each web application (I have 3 web apps) and I cannot find absolute path C:\inetpub\custerr anywhere. I have also checked web.config for each web application. Where else should I search? In event viewer this error could be found:

Event code: 3005

Event message: An unhandled exception has occurred.

Event time:

Event time

Event ID: d27a2d889cb74d2b944b57fa486fdc70

Event sequence: 4

Event occurrence: 1

Event detail code: 0

Application information:

    Application domain: /LM/W3SVC/1/ROOT/IdentityManager2-1-130191405973015759

    Trust level: Full

    Application Virtual Path: /IdentityManager2

    Application Path: C:\inetpub\wwwroot\IdentityManager2\

    Machine name:

Process information:

    Process ID: 5060

    Process name: w3wp.exe

    Account name: IIS APPPOOL\IdentityManager2_POOL

Exception information:

    Exception type: WebDesignerException

    Exception message: The web project could not be loaded.

Request information:

    Request URL: ....IdentityManager2/page.axd/

    Request path: /IdentityManager2/page.axd/

    User host address:

    User: 

    Is authenticated: False

    Authentication Type: 

    Thread account name: IIS APPPOOL\IdentityManager2_POOL

Thread information:

    Thread ID: 6

    Thread account name: IIS APPPOOL\IdentityManager2_POOL

    Is impersonating: False

    Stack trace:    at VI.WebDesigner.Runtime.ConfigurationUpdater.Update()

   at VI.WebDesigner.WebApplication.InitWebApplication()

   at VI.WebDesigner.WebApplication.get_Instance()

   at VI.WebDesigner.Runtime.Communication.WebPage.get_Configuration()

   at VI.WebDesigner.Runtime.Communication.WebPage.BuildBasicDocumentStructure()

   at VI.WebDesigner.Runtime.Communication.WebPage.OnInit(EventArgs e)

   at System.Web.UI.Control.InitRecursive(Control namingContainer)

   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

Any idea?

Best regards,

Evgen