title: I seem to face this issue all of a sudden as this worked for a few weeks. Does anyone have a clue on what could cause this?
body: <p>An exceptionCaught() event was fired, and it reached at the tail of the pipeline. It usually means the last handler in the pipeline did not handle the exception.
  at io.netty.channel.DefaultChannelPipeline.callHandlerAdded0(DefaultChannelPipeline.java:624)
  at io.netty.channel.DefaultChannelPipeline.access$100(DefaultChannelPipeline.java:46)
  at io.netty.channel.DefaultChannelPipeline$PendingHandlerAddedTask.execute(DefaultChannelPipeline.java:1463)
  at io.netty.channel.DefaultChannelPipeline.callHandlerAddedForAllHandlers(DefaultChannelPipeline.java:1115)
  at io.netty.channel.DefaultChannelPipeline.invokeHandlerAddedIfNeeded(DefaultChannelPipeline.java:650)
  at io.netty.channel.AbstractChannel$AbstractUnsafe.register0(AbstractChannel.java:502)
  at io.netty.channel.AbstractChannel$AbstractUnsafe.access$200(AbstractChannel.java:417)
  at io.netty.channel.AbstractChannel$AbstractUnsafe$1.run(AbstractChannel.java:474)
  at io.netty.util.concurrent.AbstractEventExecutor.safeExecute$$$capture(AbstractEventExecutor.java:164)
  at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java)
  at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
  at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
  at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
  at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
  at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
  at java.base/java.lang.Thread.run(Thread.java:834)
  io.netty.channel.ChannelPipelineException: reactor.netty.resources.PooledConnectionProvider$PooledConnectionAllocator$PooledConnectionInitializer.handlerAdded() has thrown an exception; removed.
  at io.netty.channel.DefaultChannelPipeline.callHandlerAdded0(DefaultChannelPipeline.java:624)
  at io.netty.channel.DefaultChannelPipeline.access$100(DefaultChannelPipeline.java:46)
  at io.netty.channel.DefaultChannelPipeline$PendingHandlerAddedTask.execute(DefaultChannelPipeline.java:1463)
  at io.netty.channel.DefaultChannelPipeline.callHandlerAddedForAllHandlers(DefaultChannelPipeline.java:1115)
  at io.netty.channel.DefaultChannelPipeline.invokeHandlerAddedIfNeeded(DefaultChannelPipeline.java:650)
  at io.netty.channel.AbstractChannel$AbstractUnsafe.register0(AbstractChannel.java:502)
  at io.netty.channel.AbstractChannel$AbstractUnsafe.access$200(AbstractChannel.java:417)
  at io.netty.channel.AbstractChannel$AbstractUnsafe$1.run(AbstractChannel.java:474)
  at io.netty.util.concurrent.AbstractEventExecutor.safeExecute$$$capture(AbstractEventExecutor.java:164)
  at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java)
  at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
  at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:500)
  at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
  at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
  at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
  at java.base/java.lang.Thread.run(Thread.java:834)
  Caused by: java.util.NoSuchElementException: reactor.netty.resources.PooledConnectionProvider$PooledConnectionAllocator$PooledConnectionInitializer
  at io.netty.channel.DefaultChannelPipeline.getContextOrDie(DefaultChannelPipeline.java:1082)
  at io.netty.channel.DefaultChannelPipeline.remove(DefaultChannelPipeline.java:417)
  at reactor.netty.resources.PooledConnectionProvider$PooledConnectionAllocator$PooledConnectionInitializer.handlerAdded(PooledConnectionProvider.java:284)
  at io.netty.channel.AbstractChannelHandlerContext.callHandlerAdded(AbstractChannelHandlerContext.java:938)
  at io.netty.channel.DefaultChannelPipeline.callHandlerAdded0(DefaultChannelPipeline.java:609)
  ... 15 common frames omitted</p>
  <p><strong>Edit 1</strong></p>
  <p>Thanks for the pointer. I see only below netty related things in dependency tree.<br />
  I am not sure which mismatch would cause the issue.</p>
  <p>webclient app dependency tree
  [INFO] |  +- org.springframework.boot:spring-boot-starter-reactor-netty:jar:2.3.4.RELEASE:compile
  [INFO] |  |  - io.projectreactor.netty:reactor-netty:jar:0.9.12.RELEASE:compile
  [INFO] |  |     - io.netty:netty-handler-proxy:jar:4.1.52.Final:compile
  [INFO] |  |        - io.netty:netty-codec-socks:jar:4.1.52.Final:compile</p>
  <p>parent dependency tree</p>
  <pre><code>[INFO] |  |  |  |  |  \- software.amazon.awssdk:netty-nio-client:jar:2.10.91:runtime
  [INFO] |  |  |  |  |     \- com.typesafe.netty:netty-reactive-streams-http:jar:2.0.4:runtime
  [INFO] |  |  |  |  |        \- com.typesafe.netty:netty-reactive-streams:jar:2.0.4:runtime
  [INFO] |  |  |  |  +- io.netty:netty-codec-http:jar:4.1.54.Final:compile
  [INFO] |  |  |  |  |  +- io.netty:netty-common:jar:4.1.54.Final:compile
  [INFO] |  |  |  |  |  +- io.netty:netty-buffer:jar:4.1.54.Final:compile
  [INFO] |  |  |  |  |  +- io.netty:netty-transport:jar:4.1.54.Final:compile
  [INFO] |  |  |  |  |  |  \- io.netty:netty-resolver:jar:4.1.54.Final:compile
  [INFO] |  |  |  |  |  +- io.netty:netty-codec:jar:4.1.54.Final:compile
  [INFO] |  |  |  |  |  \- io.netty:netty-handler:jar:4.1.54.Final:compile
  [INFO] |  |  |  |  +- io.netty:netty-codec-http2:jar:4.1.54.Final:compile
  [INFO] |  |  |  |  +- io.netty:netty-transport-native-epoll:jar:linux-x86_64:4.1.54.Final:compile
  [INFO] |  |  |  |  |  \- io.netty:netty-transport-native-unix-common:jar:4.1.54.Final:compile
  
  [INFO] |  |  +- io.netty:netty-handler:jar:4.1.53.Final:compile
  [INFO] |  |  |  \- io.netty:netty-resolver:jar:4.1.53.Final:compile
  [INFO] |  \- io.netty:netty-transport-native-epoll:jar:linux-x86_64:4.1.51.Final:compile
  [INFO] |     +- io.netty:netty-common:jar:4.1.51.Final:compile
  [INFO] |     +- io.netty:netty-buffer:jar:4.1.51.Final:compile
  [INFO] |     +- io.netty:netty-transport:jar:4.1.51.Final:compile
  [INFO] |     \- io.netty:netty-transport-native-unix-common:jar:4.1.51.Final:compile
  [INFO] |  |     \- io.netty:netty-tcnative-boringssl-static:jar:2.0.30.Final:compile
  [INFO] |  |  \- software.amazon.awssdk:netty-nio-client:jar:2.10.91:runtime
  [INFO] |  |     \- com.typesafe.netty:netty-reactive-streams-http:jar:2.0.4:runtime
  [INFO] |  |        \- com.typesafe.netty:netty-reactive-streams:jar:2.0.4:runtime
  [INFO] |  +- io.netty:netty-codec-http:jar:4.1.53.Final:compile
  [INFO] |  |  \- io.netty:netty-codec:jar:4.1.53.Final:compile
  [INFO] |  +- io.netty:netty-codec-http2:jar:4.1.53.Final:compile
  </code></pre>