HTTP 101 Switching Protocols vs 523 Origin Is Unreachable
HTTP 101 (Switching Protocols) is a 1xx Informational response, while 523 (Origin Is Unreachable) is a 5xx Server Error response. 101 indicates that the server understands the Upgrade header field request and indicates which protocol it is switching to. In contrast, 523 means that cloudflare-specific. Cloudflare could not reach the origin server (DNS resolution failed or no route).
Description
The server understands the Upgrade header field request and indicates which protocol it is switching to.
Quand vous le voyez
When upgrading from HTTP/1.1 to WebSocket, or to HTTP/2.
Comment résoudre
This is normal behavior during protocol upgrades. Ensure your client supports the target protocol.
Description
Cloudflare-specific. Cloudflare could not reach the origin server (DNS resolution failed or no route).
Quand vous le voyez
When Cloudflare's DNS for the origin fails to resolve.
Comment résoudre
Verify DNS records in Cloudflare dashboard. Check origin server's IP address.
Différences clés
101 is a 1xx Informational response, while 523 is a 5xx Server Error response.
HTTP 101: The server understands the Upgrade header field request and indicates which protocol it is switching to.
HTTP 523: Cloudflare-specific. Cloudflare could not reach the origin server (DNS resolution failed or no route).
You encounter 101 when when upgrading from HTTP/1.1 to WebSocket, or to HTTP/2.
You encounter 523 when when Cloudflare's DNS for the origin fails to resolve.
Quand utiliser lequel
For 101 (Switching Protocols): This is normal behavior during protocol upgrades. Ensure your client supports the target protocol. For 523 (Origin Is Unreachable): Verify DNS records in Cloudflare dashboard. Check origin server's IP address.