HTTP 426 Upgrade Required vs 508 Loop Detected
HTTP 426 (Upgrade Required) is a 4xx Client Error response, while 508 (Loop Detected) is a 5xx Server Error response. 426 indicates that the server refuses to perform the request using the current protocol but might after the client upgrades to a different protocol. In contrast, 508 means that the server detected an infinite loop while processing the request (WebDAV).
Description
The server refuses to perform the request using the current protocol but might after the client upgrades to a different protocol.
When You See It
When a server requires HTTPS or a newer protocol version.
How to Fix
Switch to the protocol specified in the Upgrade response header.
Description
The server detected an infinite loop while processing the request (WebDAV).
When You See It
When WebDAV encounters circular references in bindings.
How to Fix
Fix the circular reference in the WebDAV configuration.
Key Differences
426 is a 4xx Client Error response, while 508 is a 5xx Server Error response.
HTTP 426: The server refuses to perform the request using the current protocol but might after the client upgrades to a different protocol.
HTTP 508: The server detected an infinite loop while processing the request (WebDAV).
You encounter 426 when when a server requires HTTPS or a newer protocol version.
You encounter 508 when when WebDAV encounters circular references in bindings.
When to Use Which
For 426 (Upgrade Required): Switch to the protocol specified in the Upgrade response header. For 508 (Loop Detected): Fix the circular reference in the WebDAV configuration.