101101 Switching Protocols
The server is switching protocols as requested by the client via an Upgrade header.
423The resource being accessed is locked and cannot be modified (WebDAV).
Another user or process has locked the resource. In WebDAV, resources can be locked for exclusive editing. The lock prevents other users from making changes until it is released.
Wait for the lock to be released, or request the lock owner to unlock the resource. Check the Lock-Token header for details. Use UNLOCK to release the lock if you own it.
101The server is switching protocols as requested by the client via an Upgrade header.
425The server is unwilling to process a request that might be replayed, to avoid potential replay attacks.
200The request has succeeded. The meaning of the success depends on the HTTP method used.
501The server does not support the functionality required to fulfill the request.
521The origin web server has refused the connection from Cloudflare.
522Cloudflare could not negotiate a TCP handshake with the origin server.