IIS 7 and Above
Disable HTTP2 support on Windows 2016 Server
Last post Sep 14, 2017 08:53 AM by Ron van Pol
Sep 13, 2017 03:23 PM|Ron van Pol|LINK
Is it possible to disable HTTP2 support on Windows 2016 Server. I know that IIS will fallback to HTTP 1.1 when the client doesn't support it. But because we are using NTLM/Kerberos for authentication (which are not supported for HTTP2 by IIS 10), I want
to disable HTTP2 support alltogether. I've seen posts mentioning registry settings but they only work on Windows 10 clients or Windows 2016 Server preview version. None of the registry settings work for the final Windows 2016 Server version.
Sep 14, 2017 01:47 AM|mahamr|LINK
When Windows Authentication is being used, HTTP/1.1 will still be used without issue, even when HTTP/2 is enabled. Out of curiosity, why disable it altogether if the server will fallback gracefully anyways?
Sep 14, 2017 02:41 AM|Yuk Ding|LINK
Hi Ron van Pol,
Why do you want to disable HTTP/2 for IIS while it is more secure and faster? If any configuration in IIS would not support http/2, then it should roll back to http/1.1 automatically. Modifying the registry EnableHttp2Tls and EnableHttp2Cleartext also
need a reboot for your server. So have you tried to reboot the server after modifying the registry key? If it is unavailable, maybe you could only use http instead of http/2. Or you could try to use clear text which is not supported in HTTP/2. I'm not sure
whether it is necessary to disable http/2.
Sep 14, 2017 08:53 AM|Ron van Pol|LINK
We are doing authentication using NTLM (in a secure environment i must add) and we are experiencing problems with Chrome and older versions of Firefox. See https://bugs.chromium.org/p/chromium/issues/detail?id=685741 for
a description of the bug in Chrome. The same bug was present in Firefox but their latest version fixed the bug but still the bug in Chrome remains. As a workaround I wanted to disable HTTP/2 alltogether.
In the meantime I have managed to disable HTTP/2 in IIS by adding two registry keys, see https://gist.github.com/nicksterx/8cabfd5c696bd23f8ab4f11ca112cb26.