How To Fix Origin Unreachable Error Code 523

The “Origin Unreachable” error code 523 is a common issue faced by websites using Cloudflare as their content delivery network (CDN) and DNS service. This HTTP status code indicates that Cloudflare’s servers are unable to connect to the origin server that hosts the actual website content.

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When this happens, website visitors may see error messages instead of the site content. Fixing this issue is crucial for restoring normal access to your website. Thankfully, there are several troubleshooting steps you can take to resolve the error 523 and get your site back online.

What Causes the Origin Unreachable Error 523?

Before diving into the fixes, it helps to understand what causes the error 523 in the first place.

Potential reasons include:

  • Origin server being offline or unavailable
  • Incorrect DNS settings redirecting Cloudflare to the wrong IP address
  • Firewalls blocking connections from Cloudflare IPs to your origin
  • Invalid or expired SSL/TLS certificates on the origin server
  • General issues with the Cloudflare CDN network

Essentially any connectivity or configuration issues that prevent Cloudflare servers from reaching your origin can result in the misleading “Origin Unreachable” error.

Step-By-Step Guide To Troubleshooting Error 523

When you encounter the origin unreachable 523 status from Cloudflare, follow these steps to uncover and resolve the issue:

1. Check The Origin Server Status

First, check whether your origin server is actually online and functioning properly. Log in to your hosting provider’s control panel or server admin tools to verify the status.

If the origin is offline or unreachable even directly, that is likely the cause of the 523 error. You’ll need to address the server problems first before troubleshooting further.

2. Confirm DNS Settings Are Correct

One overlooked cause of the Cloudflare 523 error is incorrect DNS settings that point Cloudflare servers to the wrong IP address for your origin.

Carefully check that your DNS A/AAAA records are properly configured to direct traffic to your web server’s current IP address. Keep in mind that any changes can take time to propagate across networks.

3. Whitelist Cloudflare IP Addresses

In some cases, firewall policies intentionally or accidentally block Cloudflare IPs from accessing the origin infrastructure.

Cloudflare publishes a list of IP ranges used by its proxy services. Add these IP addresses to your firewall whitelist rules so that Cloudflare traffic can reliably reach your origin.

4. Verify Firewall Rules Are Not Blocking Access

Beyond the Cloudflare IP ranges, also double check that your firewall, security groups, or access control lists are not blocking connections in general from external hosts to your web server.

Temporarily adjust the rules to allow traffic to the origin port and IP while testing to see if that resolves the 523 status from Cloudflare.

5. Validate SSL/TLS Certificates

While less common nowadays, expired or invalid SSL/TLS certificates on your web server can also cause Cloudflare’s proxies to fail. This prevents proper connections for visitors.

Test the TLS connection locally to confirm there are no certificate errors. If needed, renew or replace the SSL certificates on the origin.

6. Check Cloudflare Status Page For Issues

Service issues with the Cloudflare CDN itself can also prevent connectivity to origins, so the problem may not be on your infrastructure.

Consult Cloudflare’s system status page at to check if any ongoing issues or outages match the timing of your site’s 523 errors.

7. Try Waiting A Few Minutes

In rare cases, the Unreachable Origin error is temporary and resolves on its own after a few minutes. Before making major changes to your site or DNS, try waiting a bit to see if Cloudflare reconnects on its own.

Reaching Out for Additional Support

If the above steps do not resolve the Cloudflare error 523, you may need to open a support ticket with either Cloudflare or your hosting provider explaining when the issue began and what troubleshooting you have already attempted.

Include any details around DNS changes, firewall rule changes, or origin server events that occurred just before the initial errors, as that can aid troubleshooting.

Some additional steps support engineers may take include:

  • Traceroutes to pinpoint connectivity gaps
  • Adjusting Load Balancer configs
  • Subnet Access list modifications
  • Testing alternate origin server infrastructure

With collaborative troubleshooting and a systematic approach, even stubborn error 523 problems can typically be overcome. The key is not making assumptions and instead methodically eliminating variables until root cause is found.

Troubleshooting StepDetails
Check Origin Server StatusConfirm origin is online and operational
Verify DNS SettingsValidate DNS records pointing Cloudflare correctly
Whitelist Cloudflare IPsAllow CDN access through firewalls/security groups
Review Firewall RulesCheck for overly restrictive policies blocking traffic
Validate SSL/TLS CertificatesResolve any expired or invalid certificates
Check Cloudflare System StatusRule out larger CDN issues
Wait A Few MinutesError 523 sometimes resolves on its own

Preventing Future Error 523 Occurrences

Once the immediate issue is fixed, some add-on steps to help minimize future error 523 incidents include:

  • Setting up origin health checks & monitoring to detect outages faster
  • Automating SSL/TLS certificate renewal well ahead of expirations
  • Regularly reviewing firewall rules for relevance and security
  • Enforcing DNS settings for accuracy, preventing route hijacking
  • Subscribing to Cloudflare system status notifications
  • Load testing origins to validate robust capacity

Building resilience into architecture and operations helps minimize outages and reduces how long an origin unreachable condition persists even if one occurs.

Quickly diagnosing and resolving error 523 also protects your website uptime and reputation with visitors. By methodically following troubleshooting steps and seeking help when needed, you can overcome these Cloudflare errors.


Cloudflare’s obscure “Error 523” messaging hardly hints at the range of possible issues – from server outages to firewall blocks to CDN failures – that can prevent connecting to your origin infrastructure.

Hopefully this guide has demystified the error and provided a solid troubleshooting roadmap to restore website availability when you encounter “Origin Unreachable” issues. Addressing problems systematically and documenting solutions will also help prevent and minimize future instances of the error 523.

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