We have a setup of from end ARR server routing the request to backend IIS server.In my application there is a functionality of downloading a pdf file which is being called by a .axd file,The .axd file do not reside in the file system which is autogenerated by http handler.Now the this download PDF functionality is working fine in backend IIS server.But when we try to download the pdf in reverse proxy ARR server it gives a 502 error.I implemented failed request tracing in ARR and found
MODULE_SET_RESPONSE_ERROR_STATUS
Modulename ApplicationrequestRouting
Notification 128
HTTPSStatus 502
HTTPreason Bad Gateway
HttpSubstatus 3
ErrorCode 2147954552
ConfigexceptionInfo
Notification EXECUTE_REQUEST_HANDLER
Also in the ARR server IIS log it shows 502.3 error while executing the .axd file.
Is it something to do with URL rewrite or may be the firewall could be an issue .ARR is in DMZ and IIS in trusted zone and there is a firewall in between.What can be the best solution to trace the issue.