KEMP & Exchange – HTTP 400 Bad Request When Using Exchange Connectivity Analyzer



I recently encountered an error when test Autodiscover at a client site, using the Exchange Connectivity Analyzer. The Error we saw was:

A Web exception occurred because an HTTP 400 – BadRequest response was received from Unknown

The error came in the POST check of the Autodiscover services.

The Exchange environment was using KEMP LoadMasters as a Reverse Proxy for the Exchange web services.

Similar issue has been documented by Brian Reid: Exchange Web Services (EWS) and 501 Error and Bhargav Shukla.

The Solution:

The solution to my problem, was to set “100-Continue Handling” of the KEMP, to “RFC-7231 Compliant” instead of the default value “RFC-2616 Compliant”.

This setting is found under the L7 Configuration of the KEMP LoadMaster:


After changing the setting, everything now works and all tests came out “Green”:


About Author

Peter is an Exchange specialist with over 15+ years of experience with Exchange Server and certified Microsoft Certified Master (MCM) and Microsoft Certified Solutions Master (MCSM) on Exchange Server. He has been awarded the Microsoft MVP award, every year since 2007. He is active in the Microsoft community and User Group Leader for CoLabora (a danish UC & Cloud User Group). He works as an Cloud & Infrastructure Architect and Consulent, with primary focus on Exchange, Office 365, Azure and Skype for Business.

1 Comment

Copyright 2005-2015 - Peter Schmidt.