---
set: 1
code: 101
title: Switching Protocols
references:
    "Rails HTTP Status Symbol": ":switching_protocols"
---

The 101 Switching Protocols status code indicates that the server understands
and is willing to comply with the client's request, via the Upgrade header field
([Section 6.7 of RFC7230][2]), for a change in the application protocol being
used on this connection.

The server MUST generate an Upgrade header field in the
response that indicates which protocol(s) will be switched to immediately after
the empty line that terminates the 101 response.

It is assumed that the server will only agree to switch protocols when it is
advantageous to do so. For example, switching to a newer version of HTTP might
be advantageous over older versions, and switching to a real-time, synchronous
protocol might be advantageous when delivering resources that use such features.

Source: [RFC7231 Section 6.2.2][1]

[1]: <http://tools.ietf.org/html/rfc7231#section-6.2.2>
[2]: <http://tools.ietf.org/html/rfc7230#section-6.7>