523 Origin Is Unreachable

What HTTP 523 Origin Is Unreachable Means

Cloudflare cannot reach the origin server at all.

A Cloudflare-specific code: the origin appears unreachable, usually due to DNS or routing problems.

Common Causes

• Incorrect origin IP / A record in DNS
• Origin server offline
• Routing or BGP problem to the origin
• Origin hosting provider outage

How to Fix It (For Visitors)

• Try again later
• Contact the website owner

How to Fix It (For Developers/Admins)

• Verify the origin IP in Cloudflare DNS is correct
• Confirm the origin is online and reachable
• Check the hosting provider status
• Test connectivity from outside your network

Returning a 523 Origin Is Unreachable (Code Examples)

If you build APIs or web apps, here is how to send an HTTP 523 response and how to test for it:

Node.js (Express)

app.get('/resource', (req, res) => {
  res.status(523).json({ error: 'Origin Is Unreachable' });
});

Python (Flask)

@app.route('/resource')
def resource():
    return jsonify(error='Origin Is Unreachable'), 523

PHP

<?php
http_response_code(523);
header('Content-Type: application/json');
echo json_encode(['error' => 'Origin Is Unreachable']);

Check the status with curl

curl -I https://example.com/resource
# Look for: HTTP/1.1 523 Origin Is Unreachable

Frequently Asked Questions

What does HTTP 523 Origin Is Unreachable mean?

A Cloudflare-specific code: the origin appears unreachable, usually due to DNS or routing problems. In short: Cloudflare cannot reach the origin server at all.

Is a 523 Origin Is Unreachable error my fault or the website's?

523 is a 5xx server-error code, so the problem is on the server side, not your browser or device. As a visitor you can usually only retry; if you run the site, investigate the server.

How do I fix a 523 Origin Is Unreachable error?

Verify the origin IP in Cloudflare DNS is correct. Confirm the origin is online and reachable. Check the hosting provider status.

Official Specification

The 523 Origin Is Unreachable status code is defined in Cloudflare (non-standard).

View the IANA HTTP Status Code Registry →