What it means
With a 523, Cloudflare can't reach the origin address, most often because DNS points to a wrong or outdated IP, or because routing to the origin is broken.
Most common causes
- The server's IP changed but the DNS at Cloudflare wasn't updated.
- A wrong A or AAAA record (e.g. an unreachable IPv6 address).
- A routing problem at the hosting provider.
What you can do as a visitor
- The site is unreachable. Try again later.
What the site owner or developer should do
- Check the A/AAAA records in Cloudflare DNS and compare them with the server's actual IP.
- If an AAAA record points to non-working IPv6, remove or fix it.
- Contact your hosting provider about a possible network problem.
Impact on SEO and Google
As with other 5xx errors: prolonged unavailability puts your indexing at risk.
Frequently asked questions
What most often causes a 523?
An outdated or wrong origin IP in DNS.
How do I check DNS records?
Use a DNS lookup tool to check the domain's A and AAAA records.