Topic: Apache 2.2 ProxyPass to IIS 8.0 - Intermittent Errors

[au_z71]

Hi Forum,

I have a externally facing URL which is load balanced through an F5 load balancer. That URL is balanced between two Apache 2.2 servers which then proxy the information to the two internal Windows Server 2012 servers running IIS 8.0. Occasionally, we get this error:
"Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log."

After refreshing the page, sometimes taking up to 4 refreshes of the page, the error goes away and the application loads and runs without any issues.

This is the error that is in the Apache log:
[error] (103)Software caused connection abort: proxy: pass request body failed to <IP_Removed>
[error] (103)Software caused connection abort: proxy: pass request body failed to <IP_Removed> from <IP_Removed>

This is the current config on Apache:
<Proxy balancer://app_name>
BalancerMember http://server_name_1/app_name
BalancerMember http://server_name_2/app_name
ProxySet lbmethod=byrequests maxattempts=20
</Proxy>
ProxyPass /app_name balancer://app_name
ProxyPassReverse /app_name balancer://app_name

Any ideas on how we can resolve this issue?

[James Blond]

I've seen that error using a SSL backend or a buggy backend server. Sometimes it helped to disable KeepAlive to the backend server.

The reverse proxy handling is much better with Apache 2.4. Also 2.2 is almost EOL.

[au_z71]

We found the issue after a several days of researching. After adding the below settings, we were able to resolve the issue.

# Define the server wide KeepAlive states
Timeout 300
ProxyTimeout 120
SetEnv force-proxy-request-1.0 1
SetEnv proxy-nokeepalive 1
SetEnv proxy-initial-not-pooled 1
KeepAlive On
MaxKeepAliveRequests 150
KeepAliveTimeout 15