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Unable to Validate Webservice while initializing workflow. Error adding vDir HTTP://.... System.NullReferenceException: Object reference not set to an instance of an object.


Article ID: 172176


Updated On:


Workflow Solution


Workflow throws an error while trying to verify access to webservices.  The services still function but the message is noted in the Workfflow and Event Viewer logs.

"Error adding vDir HTTP://(enter URL here)" error appears in the logs.
LogicBase.ServerExtensions.WebServiceSearcher throws a "System.NullReferenceException: Object reference not set to an instance of an object." error


A custom script that prepared IIS configuration options included an entry for  "HTTP Response Headers" had a corrupt name entry value that included spaces.  Spaces are not supported in the name for "HTTP Response Headers" 


Workflow 8.1 RU6


Fix the HTTP Response Headers in IIS. 

  1. Open Internet Information Services.  Start>Run>INETMGR
  2. Find the default website or the virtual directory of the webservice.
  3. Under the “IIS” heading in the right-hand pane, double-click on “HTTP Response Headers.”
  4. Right-click on the custom HTTP header that includes the space and select Edit to fix it or remove it.

It should be noted that Workflow publishing techniques, either publishing from Workflow Designer, or using generated pre-configured installation packages DO NOT require any custom changes to IIS settings prior to or post installation.