Sucuri Firewall Error Codes: Troubleshooting and Solutions

1. 404 Errors

A 404 error may affect the entire site, so ensure the correct host IP or name is set as the source. If the 404 is Sucuri-branded, ensure your DNS A record points to the correct Sucuri WAF IP. If only a single page or project is affected, replace the missing resource or remove its reference in the site code.

2. 302 Errors

Redirect loops are often identified by browser errors, but caching loops from the host may be the cause. Switching to site caching may help. Disabling an HTTP-only site in the SSL tab may conflict with 301 redirects. If redirecting an HTTP address to https, use an HTTP-only site if possible.

3. 401 Errors

The host sends messages requiring login to view a resource, typically seen when visiting pages that typically require login.

4. 500 and 501 Errors

Internal server messages, originating from the hosting server, often indicate misconfiguration issues. Checking the host’s error log should reveal the root cause.

5. 502 Errors

Sucuri-branded issues are typically caused by a hosting server firewall blocking the WAF IP. Check IP ranges 192.88.134.0/23, 185.93.228.0/22, 66.248.200.0/22, 2a02:fe80::/29, and 208.109.0.0/22, which should be whitelisted by the host. If you are unable to find the cause, open a support ticket for an error log.

6. 503 Errors

This could be due to resource issues, misconfiguration, or database errors. Check the host’s access and error logs to identify the cause. Unusual loads, whether legitimate or a DDoS attack, should also be investigated, requiring immediate contact with Sucuri.

7. 504 Errors

Similar to 502 errors, 504 errors are Sucuri-branded and can be caused by a firewall blocking the WAF IP. Whitelist the IP range, as with 502 errors. 504 errors are usually caused by the host failing to respond within 180 seconds. Request Sucuri’s error log and verify with the host’s error log to identify the cause.