Exception when requesting enrich statistics

[consulthys]

Elasticsearch version (bin/elasticsearch --version):
7.9.1

Plugins installed:
N/A

JVM version (java -version):
Elastic Cloud

OS version (uname -a if on a Unix-like system):
Elastic Cloud

Description of the problem including expected versus actual behavior:
When trying to view the stats of an executing enrich policy, I get the following error:

GET _enrich/_stats
->
{
  "error" : {
    "root_cause" : [
      {
        "type" : "transport_serialization_exception",
        "reason" : "Failed to deserialize response from handler [org.elasticsearch.transport.TransportService$ContextRestoreResponseHandler]"
      }
    ],
    "type" : "transport_serialization_exception",
    "reason" : "Failed to deserialize response from handler [org.elasticsearch.transport.TransportService$ContextRestoreResponseHandler]",
    "caused_by" : {
      "type" : "illegal_argument_exception",
      "reason" : "Unknown NamedWriteable [org.elasticsearch.tasks.Task$Status][enrich-policy-execution]"
    }
  },
  "status" : 500
}

If I try to view the task directly I get a similar error:

GET _tasks?actions=policy*&detailed
->
{
  "node_failures" : [
    {
      "type" : "failed_node_exception",
      "reason" : "Failed node [IDAjxBxmQnmmGWH0T6trLA]",
      "node_id" : "IDAjxBxmQnmmGWH0T6trLA",
      "caused_by" : {
        "type" : "transport_serialization_exception",
        "reason" : "Failed to deserialize response from handler [org.elasticsearch.transport.TransportService$ContextRestoreResponseHandler]",
        "caused_by" : {
          "type" : "illegal_argument_exception",
          "reason" : "Unknown NamedWriteable [org.elasticsearch.tasks.Task$Status][enrich-policy-execution]"
        }
      }
    }
  ],
  "nodes" : { }
}

Steps to reproduce:

1. Create an enrich policy
2. Execute it
3. Try to hit the _enrich/_stats endpoint

Provide logs (if relevant):

In the logs I'm seeing the following

java.lang.IllegalStateException: Message not fully read (response) for requestId [35936233], handler [org.elasticsearch.transport.TransportService$ContextRestoreResponseHandler/org.elasticsearch.transport.TransportService$6@18ae686f], error [false]; resetting",
                "at org.elasticsearch.transport.InboundHandler.messageReceived(InboundHandler.java:124) ~[elasticsearch-7.9.1.jar:7.9.1]",
                "at org.elasticsearch.transport.InboundHandler.inboundMessage(InboundHandler.java:78) ~[elasticsearch-7.9.1.jar:7.9.1]",
                "at org.elasticsearch.transport.TcpTransport.inboundMessage(TcpTransport.java:692) [elasticsearch-7.9.1.jar:7.9.1]",
                "at org.elasticsearch.transport.InboundPipeline.forwardFragments(InboundPipeline.java:142) [elasticsearch-7.9.1.jar:7.9.1]",
                "at org.elasticsearch.transport.InboundPipeline.doHandleBytes(InboundPipeline.java:117) [elasticsearch-7.9.1.jar:7.9.1]",
                "at org.elasticsearch.transport.InboundPipeline.handleBytes(InboundPipeline.java:82) [elasticsearch-7.9.1.jar:7.9.1]",
                "at org.elasticsearch.transport.netty4.Netty4MessageChannelHandler.channelRead(Netty4MessageChannelHandler.java:76) [transport-netty4-client-7.9.1.jar:7.9.1]",
                "at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.handler.logging.LoggingHandler.channelRead(LoggingHandler.java:271) [netty-handler-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.handler.ssl.SslHandler.unwrap(SslHandler.java:1518) [netty-handler-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.handler.ssl.SslHandler.decodeJdkCompatible(SslHandler.java:1267) [netty-handler-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.handler.ssl.SslHandler.decode(SslHandler.java:1314) [netty-handler-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:501) [netty-codec-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:440) [netty-codec-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:276) [netty-codec-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:714) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.nio.NioEventLoop.processSelectedKeysPlain(NioEventLoop.java:615) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:578) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493) [netty-transport-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989) [netty-common-4.1.49.Final.jar:4.1.49.Final]",
                "at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) [netty-common-4.1.49.Final.jar:4.1.49.Final]",
                "at java.lang.Thread.run(Thread.java:832) [?:?]

[DaveCTurner]

This is addressed by #62364 in 7.9.2.

[consulthys]

I didn't find that issue, but thank you so much for pointing it out @DaveCTurner !