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I have run into issue when set up IIS 7 Farm for Load balancing. Add 4 server to IIS Farm with appropriate ports(8080,8081,8082,8083). Also add Inbound rule for IIS Farm. The Tomcat instances listens these ports. When i'm opening url(which i set on inbound rule), i got the following exception:

The virtual path 'null' maps to another application, which is not allowed.     
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:     
[ArgumentException: The virtual path 'null' maps to another application, which is not allowed.]
   System.Web.CachedPathData.GetVirtualPathData(VirtualPath virtualPath, Boolean permitPathsOutsideApp) +8839122
   System.Web.HttpContext.GetFilePathData() +36
   System.Web.HttpContext.GetConfigurationPathData() +26
   System.Web.Configuration.RuntimeConfig.GetConfig(HttpContext context) +43
   System.Web.Configuration.CustomErrorsSection.GetSettings(HttpContext context, Boolean canThrow) +41
   System.Web.HttpResponse.ReportRuntimeError(Exception e, Boolean canThrow, Boolean localExecute) +101
   System.Web.HttpContext.ReportRuntimeErrorIfExists(RequestNotificationStatus& status) +538

How can i solve this issue?

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Ports? Farm? You don't use different ports in an average web farm. Perhaps explaining your setup in detail would be helpful. – TristanK Mar 21 '12 at 9:50
up vote 0 down vote accepted

It's an IIS bug. Either upgrade to Server 2008 R2 or move your rewrite rules from globalRules to the individual sites (which would just be the site on which you're running your farm).

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thank you a lot – Miro Mar 21 '12 at 12:51

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