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HTTP 502 Error Page: Unable To Reach Website

This is an error page that Distil displays to client browsers when we are having issues connecting to your server.

What is this page showing me?

  • There was an error connecting to your origin servers,
  • Information about the request that failed, and
  • Tracking numbers necessary for Distil's Support Team to investigate the root cause of the error.

What is the most likely cause of this error?

In almost all cases, a 502 error indicates that the origin server failed to respond to a request within a reasonable amount of time (a minimum of 60 seconds). The most common causes and solutions include:

  • Your server may be rate limiting or blocking requests from Distil.
    Requests sent to your servers from Distil will appear to have originated from a limited set of IP addresses. As such, your firewall, load balancer, or application server may be configured to detect this as malicious behavior and attempt to block it. Make sure the Distil IP range is not subject to rate limiting or blocking.
  • There is no route to your server.
    Make sure the configuration for the impacted domain is correct in the Distil Portal. In particular, verify that the IP/CNAME is correct.

Things you should try before contacting Distil

First, determine if the issue exists when bypassing the Distil network. To do so, edit the hosts file on your computer to override normal DNS lookups for the impacted domain. You can read more about testing with a hosts file here.

If you are able to reproduce the issue when bypassing Distil, then the issue is not caused by Distil. Contact your server administrator and/or hosting provider to investigate.

  • Make sure you have whitelisted all of Distil’s IP ranges in your origin firewall.
  • Make sure your origin IP/CNAME is correct inside the Distil Portal.
  • Make sure your DNS settings are correct.
  • Make sure your origin server(s) and load balancer(s) are all online.
  • Check the resources on your origin server(s) and load balancer(s). Make sure CPU and RAM is not being maxed out by other processes, making you server(s) unable to handle new request.
  • Check if any scripts are failing or taking a very long time to execute.
  • Run a traceroute or MTR to your origin IP and check for packet loss somewhere in the network.

What do I need to send to Distil Support?

When submitting a support request to Distil to investigate this error, it is important to provide the trace information from the error page. Please don't send a screenshot, rather, copy and paste the trace information. When copied and pasted, the text will look like this (from item 3 above):

You reached this page when attempting to access http://www.example.com/ from 192.168.0.5 on 2015-12-25 01:23:45 GMT. Trace: BB1EDE86-8FA5-11E4-B9B7-AC009C5BE403 (502) via b3a86554-de04-4db6-bf5a-ae890e529127; .454 / 673

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