Dubbo+Nacos 運行異常io.netty.handler.codec.EncoderException: java.lang.NullPointerException

運行時錯誤日誌：

org.apache.dubbo.rpc.RpcException: Failed to invoke the method getById in the service com.xxx.sys.provider.ISysSqlExecuteErrLogReadProvider. Tried 3 times of the providers [192.168.20.146:20910] (1/1) from the registry 192.168.20.146:8848 on the consumer 192.168.20.146 using the dubbo version 2.7.7. Last error is: Failed to invoke remote method: getById, provider: dubbo://192.168.20.146:20910/com.xxx.sys.provider.ISysSqlExecuteErrLogReadProvider?accepts=1000&anyhost=true&application=tp-web-boss&category=providers&check=false&deprecated=false&dubbo=2.0.2&dynamic=true&generic=false&init=false&interface=com.xxx.sys.provider.ISysSqlExecuteErrLogReadProvider&methods=getById,getListPage&path=com.xxx.sys.provider.ISysSqlExecuteErrLogReadProvider&pid=11076&protocol=dubbo&qos.enable=false&register.ip=192.168.20.146&release=2.7.7&remote.application=tp-sys-provider&retries=2&revision=0.0.1-SNAPSHOT&side=consumer&sticky=false&timeout=15000&timestamp=1608622551438, cause: org.apache.dubbo.remoting.RemotingException: io.netty.handler.codec.EncoderException: java.lang.NullPointerException
io.netty.handler.codec.EncoderException: java.lang.NullPointerException
	at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:125)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730)
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:816)
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:723)
	at io.netty.handler.timeout.IdleStateHandler.write(IdleStateHandler.java:304)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730)
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:816)
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:723)
	at io.netty.channel.ChannelDuplexHandler.write(ChannelDuplexHandler.java:106)
	at org.apache.dubbo.remoting.transport.netty4.NettyClientHandler.write(NettyClientHandler.java:88)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730)
	at io.netty.channel.AbstractChannelHandlerContext.access$1900(AbstractChannelHandlerContext.java:38)
	at io.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.write(AbstractChannelHandlerContext.java:1081)
	at io.netty.channel.AbstractChannelHandlerContext$WriteAndFlushTask.write(AbstractChannelHandlerContext.java:1128)
	at io.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.run(AbstractChannelHandlerContext.java:1070)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute$$$capture(AbstractEventExecutor.java:163)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:465)
	at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
	at com.alibaba.com.caucho.hessian.io.Hessian2Output.flushBuffer(Hessian2Output.java:1428)
	at org.apache.dubbo.common.serialize.hessian2.Hessian2ObjectOutput.flushBuffer(Hessian2ObjectOutput.java:102)
	at org.apache.dubbo.remoting.exchange.codec.ExchangeCodec.encodeRequest(ExchangeCodec.java:240)
	at org.apache.dubbo.remoting.exchange.codec.ExchangeCodec.encode(ExchangeCodec.java:69)
	at org.apache.dubbo.rpc.protocol.dubbo.DubboCountCodec.encode(DubboCountCodec.java:40)
	at org.apache.dubbo.remoting.transport.netty4.NettyCodecAdapter$InternalEncoder.encode(NettyCodecAdapter.java:69)
	at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:107)
	... 24 more

	at org.apache.dubbo.rpc.cluster.support.FailoverClusterInvoker.doInvoke(FailoverClusterInvoker.java:113)
	at org.apache.dubbo.rpc.cluster.support.AbstractClusterInvoker.invoke(AbstractClusterInvoker.java:259)
	at org.apache.dubbo.rpc.cluster.interceptor.ClusterInterceptor.intercept(ClusterInterceptor.java:47)
	at org.apache.dubbo.rpc.cluster.support.wrapper.AbstractCluster$InterceptorInvokerNode.invoke(AbstractCluster.java:92)
	at org.apache.dubbo.rpc.cluster.support.wrapper.MockClusterInvoker.invoke(MockClusterInvoker.java:82)
	at org.apache.dubbo.rpc.proxy.InvokerInvocationHandler.invoke(InvokerInvocationHandler.java:74)
	at org.apache.dubbo.common.bytecode.proxy131.getById(proxy131.java)
	at com.zc.travel.webboss.interceptor.XssFilter.checkRefererWhiteList(XssFilter.java:99)
	at com.zc.travel.webboss.interceptor.XssFilter.doFilter(XssFilter.java:59)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.session.web.http.SessionRepositoryFilter.doFilterInternal(SessionRepositoryFilter.java:167)
	at org.springframework.session.web.http.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:80)
	at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
	at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.util.concurrent.ExecutionException: org.apache.dubbo.remoting.RemotingException: io.netty.handler.codec.EncoderException: java.lang.NullPointerException
io.netty.handler.codec.EncoderException: java.lang.NullPointerException
	at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:125)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730)
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:816)
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:723)
	at io.netty.handler.timeout.IdleStateHandler.write(IdleStateHandler.java:304)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730)
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:816)
	at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:723)
	at io.netty.channel.ChannelDuplexHandler.write(ChannelDuplexHandler.java:106)
	at org.apache.dubbo.remoting.transport.netty4.NettyClientHandler.write(NettyClientHandler.java:88)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730)
	at io.netty.channel.AbstractChannelHandlerContext.access$1900(AbstractChannelHandlerContext.java:38)
	at io.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.write(AbstractChannelHandlerContext.java:1081)
	at io.netty.channel.AbstractChannelHandlerContext$WriteAndFlushTask.write(AbstractChannelHandlerContext.java:1128)
	at io.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.run(AbstractChannelHandlerContext.java:1070)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute$$$capture(AbstractEventExecutor.java:163)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:465)
	at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
	at com.alibaba.com.caucho.hessian.io.Hessian2Output.flushBuffer(Hessian2Output.java:1428)
	at org.apache.dubbo.common.serialize.hessian2.Hessian2ObjectOutput.flushBuffer(Hessian2ObjectOutput.java:102)
	at org.apache.dubbo.remoting.exchange.codec.ExchangeCodec.encodeRequest(ExchangeCodec.java:240)
	at org.apache.dubbo.remoting.exchange.codec.ExchangeCodec.encode(ExchangeCodec.java:69)
	at org.apache.dubbo.rpc.protocol.dubbo.DubboCountCodec.encode(DubboCountCodec.java:40)
	at org.apache.dubbo.remoting.transport.netty4.NettyCodecAdapter$InternalEncoder.encode(NettyCodecAdapter.java:69)
	at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:107)
	... 24 more

	at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1915)
	at org.apache.dubbo.rpc.AsyncRpcResult.get(AsyncRpcResult.java:181)
	at org.apache.dubbo.rpc.protocol.AsyncToSyncInvoker.invoke(AsyncToSyncInvoker.java:61)
	at org.apache.dubbo.monitor.support.MonitorFilter.invoke(MonitorFilter.java:89)
	at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:81)
	at org.apache.dubbo.rpc.protocol.dubbo.filter.FutureFilter.invoke(FutureFilter.java:51)
	at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:81)
	at org.apache.dubbo.rpc.filter.ConsumerContextFilter.invoke(ConsumerContextFilter.java:69)
	at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:81)
	at org.apache.dubbo.rpc.listener.ListenerInvokerWrapper.invoke(ListenerInvokerWrapper.java:78)
	at org.apache.dubbo.rpc.protocol.InvokerWrapper.invoke(InvokerWrapper.java:56)
	at org.apache.dubbo.rpc.cluster.support.FailoverClusterInvoker.doInvoke(FailoverClusterInvoker.java:82)
	... 37 more

執行mvn:clean命令，再次運行項目，問題解決。