HTTP 425 Too Early vs 523 Origin Is Unreachable
HTTP 425 (Too Early) is a 4xx Client Error response, while 523 (Origin Is Unreachable) is a 5xx Server Error response. 425 indicates that the server is unwilling to risk processing a request that might be replayed. Used with TLS 1.3 early data (0-RTT). In contrast, 523 means that cloudflare-specific. Cloudflare could not reach the origin server (DNS resolution failed or no route).
Description
The server is unwilling to risk processing a request that might be replayed. Used with TLS 1.3 early data (0-RTT).
When You See It
When a server rejects a request sent as TLS 1.3 early data due to replay risk.
How to Fix
Retry the request after the TLS handshake completes.
Description
Cloudflare-specific. Cloudflare could not reach the origin server (DNS resolution failed or no route).
When You See It
When Cloudflare's DNS for the origin fails to resolve.
How to Fix
Verify DNS records in Cloudflare dashboard. Check origin server's IP address.
Key Differences
425 is a 4xx Client Error response, while 523 is a 5xx Server Error response.
HTTP 425: The server is unwilling to risk processing a request that might be replayed. Used with TLS 1.3 early data (0-RTT).
HTTP 523: Cloudflare-specific. Cloudflare could not reach the origin server (DNS resolution failed or no route).
You encounter 425 when when a server rejects a request sent as TLS 1.3 early data due to replay risk.
You encounter 523 when when Cloudflare's DNS for the origin fails to resolve.
When to Use Which
For 425 (Too Early): Retry the request after the TLS handshake completes. For 523 (Origin Is Unreachable): Verify DNS records in Cloudflare dashboard. Check origin server's IP address.