IIS 7 and Above
Application Request Routing (ARR)
Help needed with 502.6 error
Last post Jul 27, 2020 08:59 AM by Jon_Boy
Jul 16, 2020 03:19 PM|Jon_Boy|LINK
I am seeing intermittent 502.6 errors and need some help to troubeshoot further, please.
I have found documentation that explains that the error is "502.6 Forwarded request failure (ARR)" however I have not found anything which explains more about what this means. I am seeing the error on a Windows Server 2016 system with ARR 3.0. The farm being
routed to is just a local Wildfly instance at 127.0.0.1:8080. There are planty of calls routed without issue and just a very few that generate the 502.6 error.
The log also records (for sc-win32-status) 12152 which I believe means "The server response cannot be parsed." However I am unclear on what this actually means. The errorr seem to happen three times in a row and are associated with a call to a web service
which transfers a file.
Any pointers gratefully received as my searches have failed to yield any leads so far.
Thanks in advance.
Jul 16, 2020 06:12 PM|lextm|LINK
Unless you go deeper to the packets, it won't be possible to know why.
Jul 17, 2020 03:41 AM|Yuk Ding|LINK
We can't find much document about how to fix 502.6. So we need to enable both failed request tracing and etl log to trace winhttp and winet.
The way to capture etl would looks like this
logman create trace "winhttp" -ow -o winhttp.etl -p "Microsoft-Windows-WinHttp" 0xffffffffffffffff 0xff -nb 16 16 -bs 1024 -mode Circular -f bincirc -max 4096 -ets
ECHO Reproduce your issue and enter any key to stop tracing
logman stop "wininet" -ets
However, it require network monitor or dedicated software to review these logs. So if this issue is making business impact, you can open a support ticket to involve professional support engineer.
Jul 27, 2020 08:59 AM|Jon_Boy|LINK
The issue was being caused by the size of the POST exceeding the limit set in WildFly for POST requests. This resulted in WildFly terminating the connection.
Thanks for suggestions. I'm posting the answer in case it helps anyone in the future.