How to use ALPN with OpenJDK 8u252

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Tim Fox

Jul 9, 2020, 5:38:27 AM7/9/20
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Hi All,

I am trying to use ALPN in Netty with OpenJDK 8u252. Apparently this version of openJDK has backported the Java 9 ALPN APIs so the Jetty ALPN stuff shouldn't be necessary.

According to

"Starting with OpenJDK 1.8.0_252 the use of jetty-alpn-agent is not strictly required anymore since the standard ALPN APIs have been backported to OpenJDK 1.8.0_252 from Java 9"

However, when I try and start a Netty based server using OpenJDK 8u252 I get the following exception:

java.lang.NoClassDefFoundError: org/eclipse/jetty/alpn/ALPN$Provider
at io.netty.handler.ssl.JettyAlpnSslEngine.newServerEngine(
at io.netty.handler.ssl.JdkAlpnApplicationProtocolNegotiator$AlpnWrapper.wrapSslEngine(
at io.netty.handler.ssl.JdkSslContext.configureAndWrapEngine(
at io.netty.handler.ssl.JdkSslContext.newEngine(

I.e. the Netty code still seems to want to use the Jetty stuff. Any thoughts on how I configure Netty correctly so it doesn't look for the Jetty ALPN stuff when I know I'm using OpenJDK 8u252?

So I guess this must be possible somehow.

Norman Maurer

Jul 9, 2020, 5:45:15 AM7/9/20
I am pretty sure the version of netty you are using is not up to date. This was “fixed” in 4.1.49.Final:


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Raja Ngenet

Mar 6, 2024, 2:27:23 AMMar 6
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