Error: 502 bad gateway in Apache Reverse Proxy Web Agent
Article ID: 260737
Updated On: 10-04-2023
Products
Issue/Introduction
Running CA Access Gateway (SPS), this one returns the error:
502 bad gateway
Error lines are seen:
[Sun Feb 12 23:32:27.867394 2023] [proxy:error] [pid 80769:tid 139704280217344] (70007)The timeout specified has expired: AH00957: HTTPS: attempt to connect to ##.#.#.#:#### <host name>.<Your domain> failed
[Sun Feb 12 23:32:27.867432 2023] [proxy_http:error] [pid 80769:tid 139704280217344] [client ##.#.#.#:####] AH01114: HTTP: failed to make connection to backend: <host name>.<Your domain>
Cause
At first glance, error 502 bad gateway might be caused by a network problem as Mozilla documentation (1).
It's similar to the error 504 related to this KD caused by network problems (2).
Looking at the logs, the problem is outside SiteMinder and the Web Agent.
As Apache is a reverse proxy, the issue is that the backend server doesn't return the expected data to the Apache reverse proxy.
The server <host name>.<Your domain>:port doesn't return expected data from application </exampleApp/examplePage.html> to the Apache on which the Web Agent runs:
error.log:
[Sun Feb 12 22:48:57.441179 2023] [proxy:error] [pid 2121:tid 140696862312192] [client ##.#.#.#:####] AH00898: Error reading from remote server returned by </example_App/example_Page.html>
[Sun Feb 12 22:49:42.492130 2023] [proxy_http:error] [pid 2121:tid 140696870704896] (70007)The timeout specified has expired: [client ##.#.#.#:####] AH01102: error reading status line from remote server <host name>.<Your domain>:port
[...omitted for brevity...]
[Sun Feb 12 22:53:50.757169 2023] [proxy_http:error] [pid 2121:tid 140696753207040] (70007)The timeout specified has expired: [client ##.#.#.#:####] AH01102: error reading status line from remote server <host name>.<Your domain>:port
[Sun Feb 12 22:53:50.757189 2023] [proxy:error] [pid 2121:tid 140696753207040] [client ##.#.#.#:####] AH00898: Error reading from remote server returned by </example_App/example_Page.html>
The second server <host name>.<Your domain>:port doesn't return expected data from application </exmapleapplication/> to the Apache on which the Web Agent runs:
error.log
[Sun Feb 12 22:30:33.803632 2023] [proxy_http:error] [pid 206802:tid 140613512865536] (70007)The timeout specified has expired: [client ##.#.#.#:####] AH01102: error reading status line from remote server <host name>.<Your domain>:port, referrer: https://<host name>.<Your domain>/
[Sun Feb 12 22:30:33.803667 2023] [proxy:error] [pid 206802:tid 140613512865536] [client ##.#.#.#:####] AH00898: Error reading from remote server returned by </exmapleapplication/>, referrer: https://<host name>.<Your domain>/
[...omitted for brevity...]
[Sun Feb 12 23:45:43.889600 2023] [proxy_http:error] [pid 10036:tid 140613269780224] (70007)The timeout specified has expired: [client ##.#.#.#:####] AH01102: error reading status line from remote server <host name>.<Your domain>:port, referrer: https://<host name>.<Your domain>/
[Sun Feb 12 23:45:43.889635 2023] [proxy:error] [pid 10036:tid 140613269780224] [client ##.#.#.#:####] AH00898: Error reading from remote server returned by </exmapleapplication/>, referrer: https://<other host name>.<Your domain>/
Resolution
Investigate with network team and the backend servers team why the backend server was unable to return the expected data to the Apache Reverse Proxy to solve this issue.
Additional Information
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