Troubleshooting

1. Review your server's access logs for the 30 minutes before and after the error occurred.
   
2. Look at the response codes of other requests in the access logs. If they’re also failing (e.g., 502, 503, 504), the server might be overloaded or under maintenance.
   
3. Access the URL using a browser, cURL, or Wget from the machine running the applications manager.
   
1. If the response code returned in browser is 502, 503, 504, then check the URL's server for overload. 
   
2. If the response returned in browser is 200, suggesting the issue might be elsewhere.
1. Proxy Server Configuration: If your environment requires the use of a proxy server to access the URL, configure the proxy in Applications Manager. Click here to learn how to configure the proxy.
   
2. Bypass Proxy for the URL: If you have configured a proxy in Applications Manager but want to bypass it for the server Host/IP, add the Host/IP under the "Do not use proxy for addresses beginning with" section in the "Configure Proxy" page: Navigate to Settings > Product Settings > Proxy Server Settings.
   

1. Ensure that the upstream server is functioning correctly and reachable.
   
2. Admins can check the name server, firewalls, and DNS settings.
3. Admins can also check the error log for further clues. It could be a relay between other servers that suffers glitches in transit.
   

1. If the server is under heavy load, consider implementing load balancing or auto scaling.
   
2. Verify if there’s any rate limiting or throttling causing the server to reject incoming requests.
   
3. Ensure the server is not mistakenly configured for maintenance mode or temporary downtime.
   
4. Monitor server resource usage (CPU, Memory, etc.) to identify potential overloads.

In URL monitor edit page, check "If monitor detects error, re-try immediately to verify error"  option. This will allow Applications Manager to verify the server error before reporting the error thus avoiding false alerts.