io.netty.handler.codec.http2.Http2Exception: Unexpected HTTP/1.x request: POST /v1/traces

[liushutan]

i use java -javaagent:C:\Spark\Tool\Skywalking\opentelemetry-javaagent-2.16.0.jar
-Dotel.exporter=otlp
-Dotel.exporter.otlp.endpoint=http://10.58.16.21:11800
-Dotel.service.name=my-service
-Dotel.metrics.exporter=otlp
-Dotel.logs.exporter=none
-Dotel.metrics.exporter=none
-jar C:\Spark\Tool\Skywalking\metrics-demo-1.0-SNAPSHOT.jar

but server has this error:

:44 Jun 12, 2025 9:10:44 AM io.grpc.netty.NettyServerTransport notifyTerminated
2025-06-12 17:10:44 INFO: Transport failed
2025-06-12 17:10:44 io.netty.handler.codec.http2.Http2Exception: Unexpected HTTP/1.x request: POST /v1/traces
2025-06-12 17:10:44 at io.netty.handler.codec.http2.Http2Exception.connectionError(Http2Exception.java:109)
2025-06-12 17:10:44 at io.netty.handler.codec.http2.Http2ConnectionHandler$PrefaceDecoder.readClientPrefaceString(Http2ConnectionHandler.java:317)
2025-06-12 17:10:44 at io.netty.handler.codec.http2.Http2ConnectionHandler$PrefaceDecoder.decode(Http2ConnectionHandler.java:247)
2025-06-12 17:10:44 at io.netty.handler.codec.http2.Http2ConnectionHandler.decode(Http2ConnectionHandler.java:453)
2025-06-12 17:10:44 at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:530)
2025-06-12 17:10:44 at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:469)
2025-06-12 17:10:44 at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:290)
2025-06-12 17:10:44 at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)
2025-06-12 17:10:44 at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
2025-06-12 17:10:44 at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
2025-06-12 17:10:44 at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
2025-06-12 17:10:44 at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440)
2025-06-12 17:10:44 at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
2025-06-12 17:10:44 at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
2025-06-12 17:10:44 at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:801)
2025-06-12 17:10:44 at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:509)
2025-06-12 17:10:44 at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:407)
2025-06-12 17:10:44 at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997)
2025-06-12 17:10:44 at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
2025-06-12 17:10:44 at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
2025-06-12 17:10:44 at java.base/java.lang.Thread.run(Unknown Source)

[wu-sheng]

You are pushing otel data to our http2 port but via http/1 protocol.

We require http2(grpc).

[wu-sheng]

Further, you should be aware of. otel things are different from our native agents.
You should make sure you know what you are doing and expecting.