Recently, I was configuring ESB 2.2 on my BizTalk 2013 Machine, I was facing the below error

See the end of this message for details on invoking just-in-time (JIT) debugging instead of this dialog box.

**************Exception Text **************
System.NullReferenceException: Object reference not set to an instance of an object.
   at EsbConfigurationTool.Panels.WebServicesException.get_WebSiteId()

The issue was, I had not installed the IIS 6 Management compatibility tools. ESB configuration tool uses the IIS 6 Management compatibility tools to add the web artifacts to IIS.
From the server manager, I installed the below features and after which I was able to resolve the issue.

Hope this helps.

Happy Biztalking!!

Written by
Shashidharan Krishnan

Reviewed by
Jainath V R 

Microsoft India GTSC