Look below to find any errors you’re seeing, and then try the suggested next steps.


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404 Errors
This means the whole site could be affected. Make sure you have the correct host IP/cname set as origin.

If the 404 you’re seeing is Sucuri branded, make sure your DNS A records are pointing to the correct

Sucuri WAF IP.


Also check to see if it’s just a single page or item that’s affected. If so, replace the missing resource or

remove the reference to it in the site code. 404 errors may appear as broken pages caused by missing

elements such as CSS with no other error. You can identify missing resources and its reference with a

tool like WebPageTest (look in the waterfall tab).



302 Errors
Redirect loops are usually identified with an error in the browser. While the WAF won’t be the cause of

these, you could be caching a loop from the host. Changing to site caching might help. If you have HTTPs

only site set in your SSL tab, this could be conflicting with our 301 redirect, so try disabling it. If you are

redirecting your http address to https, it is preferable to use HTTPs only site, if possible.



401 Errors
These are messages from the host indicating you are required to log in to see this resource. You normally

see these when accessing a page that you would normally need to be logged in to view.



500 & 501 Errors
These are typically accompanied by an Internal Server message. They will always originate on the hosting

server and are usually related to some misconfiguration. Checking the host’s error logs should provide a

cause.



502 Errors
These will be Sucuri branded and are normally caused by a firewall on the hosting server blocking the WAF IPs. Check our IP ranges:

192.88.134.0/23 
185.93.228.0/22 
66.248.200.0/22 
2a02:fe80::/29 
208.109.0.0/22

These should be whitelisted on the host and not subject to any rate limiting. If you are still unable to find the cause, open up a support ticket to request the error logs from Sucuri so you can verify them with the host’s error logs to find the cause.



503 Errors
These are due to resource issues, misconfigurations or database errors. Check the host’s access and error

logs to find a cause. Also note, this also could be due to abnormal load, either legitimate (which the access

logs would confirm) or due to a DDoS attack, in which case you should contact Sucuri immediately.



504 Errors
Similar to the 502 errors above, these will be Sucuri branded. And like 502 errors, these can be caused by

a firewall on the hosting server blocking the WAF IPs. Make sure our IP ranges are whitelisted, as with the

502 errors. However, more often 504s are caused by the host failing to respond to a request within 180 seconds.

If you are unable to find the cause, request the error logs from Sucuri and verify them with the host’s error logs

to find the cause. Find more useful advice on troubleshooting response timeout errors here.