Siteminder with ARR - 502.7 Error

Blog Post created by prashant.samant on Mar 3, 2017

One of our production app was throwing a 502.7 error and entire team was struggling to debug it for more than 6 weeks. Finally yesterday we managed to debug the issue hence thought of writing the details here.


There is not much information available about 502.7 error on internet. this sub-status code was introduced in ARR 3.0 latest version and I have observed that this comes when the routing module fails while processing the request. Nothing much is available on the IIS logs or netsh as the data is not on wire yet.


We have a following setup in production -


F5->IIS 8.5 (Siteminder, ARR3.0) -> Tomcat app server.


After the successful login in Siteminder, when the ARR was trying to route the request to app server, it was throwing a 502.7 "parameter is incorrect" error. We enabled, failed request tracking, winhttp tracing using netsh but could not get the exact root cause of the issue.


We could determine that Siteminder could be causing some issue as when we disable Siteminder, requests were getting routed to the app server correctly.


After going through the Siteminder logs in details, we observed that there was a whitespace added to one of the custom header as "HTTP_LASTNAME =Samant" which should have been "HTTP_LASTNAME=Samant"


After removing the space from the header name, the requests started flowing.


This was a very small error but team had to spend weeks debugging it. It's not a bug in ISS or ARR or Siteminder but similar situations might come hence posting it here. I looked at all possible link available but did not get a clue so want to make sure other's life will be easier.siteminder policyserver, ARR, iis-8, 502.7, 502