NGINX Error Log Checklist
NGINX Error logs are an effective and powerful way of managing and troubleshooting your NGINX web server.
* If you haven’t read our power guide: “NGINX Logs Guide: Monitorin and Troubleshoot in Minutes” we recommend you to do so right now.
NGINX maps error logging to the following levels:
| Code | Level | Description |
| NGX_LOG_DEBUG | Debugging | A debugging level event used to troubleshoot issues |
| NGX_LOG_INFO | Information | A log level event used to record ongoing information |
| NGX_LOG_NOTICE | Notice | A logging event that indicates when a specified event occurs |
| NGX_LOG_WARN | Warning | A logging event that is not problematic, but could be an indication of wider issues |
| NGX_LOG_ERR | Error | A logging event that indicates an error |
| NGX_LOG_CRIT | Critical error | A logging event that indicates an error that needs immediate attention |
| NGX_LOG_ALERT | Alert | A logging event that indicates when a specified critical error occurs |
| NGX_LOG_EMERG | Emergency | A logging event that could seriously damage the system. |
Unlike Apache, NGINX does not directly provide error codes.
If you are using a management tool, such as the NGINX Plus dashboards these error codes are translated into a human readable format.
Otherwise, you will need to use the APIs provided by NGINX to create scripts to map them correctly. Following is a list of common error codes HTTP that require mapping.
| Code | Message | Meaning |
| 400 | Bad Request | General response that indicates a problem with the request’s syntax |
| 401 | Unauthorized | The request tried to access a restricted error that is only available to authenticated users |
| 403 | Forbidden | A 401 type error that was the result of a valid request. |
| 404 | Not Found | The web server was unable to locate the resource |
| 405 | Method Not Allowed | The request tried to access a request using the wrong HTTP command, such as using a GET command, when a POST command is required. |
| 406 | Not Acceptable | The request required additional data from an attached file, but the file is not in the correct MIME format. |
| 407 | Proxy Authentication Required | Before the request can be granted access by the system it must be authenticated by a proxy server |
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