Upgrade-Insecure-Requests

Upgrade-Insecure-Requests 是一个请求首部，用来向服务器端发送信号，表示客户端优先选择加密及带有身份验证的响应，并且它可以成功处理 upgrade-insecure-requests CSP 指令。

Header type	Request header
Forbidden header name	no

语法

Upgrade-Insecure-Requests: 1

客户端向服务器端发送信号表示它支持 upgrade-insecure-requests 的升级机制：

GET / HTTP/1.1 
Host: example.com 
Upgrade-Insecure-Requests: 1

服务器现在可以重定向到这个站点的安全版本。在响应中可以添加一个 Vary 首部，这样的话，响应就不会被缓存服务器提供给不支持升级机制的客户端了。

Location: https://example.com/ 
Vary: Upgrade-Insecure-Requests

Specification	Status	Comment
Upgrade Insecure Requests upgrade-insecure-requests	Candidate Recommendation	Initial definition.

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`Upgrade-Insecure-Requests`	Chrome Full support 44	Edge Full support 17	Firefox Full support 48	IE No support No	Opera Full support 31	Safari Full support 10.1	WebView Android Full support 44	Chrome Android Full support 44	Firefox Android Full support 48	Opera Android Full support 32	Safari iOS Full support 10.3	Samsung Internet Android Full support 4.0