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

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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:

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

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