3126093 - HTTP/1.1 is used although HTTP/2 is enabled in SAP NetWeaver system

While using an internet browser to access SAP, it is observed that HTTP/1.1 is used despite that HTTP/2 is configured at SAP.

The issue happens only when using an internet browser based on Chromium (e.g., Google Chrome, Microsoft Edge).

In addition, the authentication method used is SPNego.

If another browser is used (e.g., Mozilla FireFox), the issue does not happen.

If a Chromium based browser is used to access a resource that does not require (SPNego) authentication (e.g., "/sap/public/icman/ping"), then HTTP/2 is used as expected.

The following entries can be seen in the ICM (dev_icm) trace level 2:

[Thr <nr>] IcmTranslateAlpnResult: SapSSLGetSessionParam(ALPN): http/1.1
[Thr <nr>] IcmPlChangeProtocol: Protocol set to HTTPS
...
[Thr <nr>] HTTP request (raw) [<connection id>:

showing that the Browser did not send ALPN h2 any more, but http1.1 instead, therefore not requesting HTTP/2.

• SAP NetWeaver based system

NTLM, Windows authentication, HTTP2, HTTP/2, SPNEGO , KBA , BC-CST-IC , Internet Communication Manager , BC-FES-WGU , SAP GUI for HTML , BC-FES-ITS , SAP Internet Transaction Server , BC-WD-ABA , Web Dynpro ABAP , BC-CST , Client/Server Technology , CA-FLP-ABA , SAP Fiori Launchpad ABAP Services , BC-SEC-LGN , Authentication , Problem