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Dev_56330's avatar
Dev_56330
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Oct 20, 2017

What is the best way to troubleshoot 500 internal server errors from BIG-IP or client?

I have a single web application with multiple uris with all accessible but 1. I am getting a 500 error when accessing through the BIG-IP with LTM+APM 12.1. When going to the web server directly I am getting no error and page displays.

 

7 Replies

  • BB16's avatar
    BB16
    Icon for Nimbostratus rankNimbostratus

    Can you plz explain your issue bit more. How you are accessing from big-ip to get error 500?

     

  • 500 errors are generated from the back end servers, F5 doesn't generate these. I would use tcpdump on the internal connection to verify what is being sent to the servers. Verify this with the application team as it may be an invalid request.

     

  • I am using a single virtual server with a very vanilla LTM policy with no modifications to lan or wan optimized TCP profiles, no changes to HTTP profile, oneconnect profile used and a access policy for certificate based authentication and SSO using KCD. There is one application with the name of https://app.com with multiple URI's (https://app.com/uri1 https://app.com/uri2 and so on. I am able to authenticate successfully and access all other URI's within this application though for a single URI I am receiving the 500 internal server error.

     

    When accessing the same site by going directly to the webserver, I am able to access the URI that I was previously unable to access due to the 500 internal server error. I do not have access to the virtual server config at this point in time so I am unable to provide the config.

     

    I was curious from the community what is the best way or most common way to identify what is causing this (e.g. fiddler, httpwatch, tcpdump, app server logs, etc.)

     

  • tcpdump on load balancer will be the best choice

     

    tcpdump -ni 0.0:nnnp host -vvv -s0 -w /var/tmp/capture.pcap

     

  • The application owner reviewed his logs and this particular site was logging unknown host when users attempted to access it through the BIG-IP. DNS records were created for the floating IP and the 500 error has not returned.