SpringBoot Actuator health endpoint for neo4j throws NoSuchElementException and always returns Status.DOWN

This happens with Spring boot 3.0 and the default neo4j-java-driver version 5.2.0 or the latest 5.3.0. The JDK used is: OpenJDK 64-Bit Server VM Corretto-19.0.0.36.1

I have created a demo project with Initializr which can trigger the issue through http://localhost:8080/actuator/health

demo.zip

Here is the docker command to set up a local neo4j instance:

docker run \
    --name neo4j \
    -p7474:7474 -p7687:7687 \
    -d \
    -v $HOME/neo4j/data:/data \
    -v $HOME/neo4j/logs:/logs \
    -v $HOME/neo4j/import:/var/lib/neo4j/import \
    -v $HOME/neo4j/plugins:/plugins \
    --env NEO4J_AUTH=neo4j/test \
    [neo4j:latest]

Here is the full health endpoint json response

{
  "status": "DOWN",
  "components": {
    "diskSpace": {
      "status": "UP",
      "details": {
        "total": 994662584320,
        "free": 564777406464,
        "threshold": 10485760,
        "path": "/Users/texas/docker/neo4j-issue/demo/.",
        "exists": true
      }
    },
    "neo4j": {
      "status": "DOWN",
      "details": {
        "error": "java.util.NoSuchElementException: Source was empty"
      }
    },
    "ping": {
      "status": "UP"
    }
  }
}

Here is the full stack trace:
java.util.NoSuchElementException: Source was empty
        at reactor.core.publisher.MonoSingle$SingleSubscriber.onComplete(MonoSingle.java:174) ~[reactor-core-3.5.0.jar:3.5.0]
        at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:144) ~[reactor-core-3.5.0.jar:3.5.0]
        at reactor.core.publisher.MonoFlatMapMany$FlatMapManyInner.onComplete(MonoFlatMapMany.java:260) ~[reactor-core-3.5.0.jar:3.5.0]
        at reactor.core.publisher.FluxZip$ZipCoordinator.drain(FluxZip.java:890) ~[reactor-core-3.5.0.jar:3.5.0]
        at reactor.core.publisher.FluxZip$ZipInner.onComplete(FluxZip.java:1142) ~[reactor-core-3.5.0.jar:3.5.0]
        at reactor.core.publisher.FluxCreate$BaseSink.complete(FluxCreate.java:460) ~[reactor-core-3.5.0.jar:3.5.0]
        at reactor.core.publisher.FluxCreate$SerializedFluxSink.drainLoop(FluxCreate.java:247) ~[reactor-core-3.5.0.jar:3.5.0]
        at reactor.core.publisher.FluxCreate$SerializedFluxSink.drain(FluxCreate.java:213) ~[reactor-core-3.5.0.jar:3.5.0]
        at reactor.core.publisher.FluxCreate$SerializedFluxSink.complete(FluxCreate.java:204) ~[reactor-core-3.5.0.jar:3.5.0]
        at org.neo4j.driver.internal.reactivestreams.InternalReactiveResult.lambda$createRecordConsumer$3(InternalReactiveResult.java:95) ~[neo4j-java-driver-5.2.0.jar:5.2.0-e0e5b6a8d95e38084c5cf9ac39e3ee8c9f5f05d0]
        at org.neo4j.driver.internal.handlers.pulln.BasicPullResponseHandler.complete(BasicPullResponseHandler.java:252) ~[neo4j-java-driver-5.2.0.jar:5.2.0-e0e5b6a8d95e38084c5cf9ac39e3ee8c9f5f05d0]
        at org.neo4j.driver.internal.handlers.pulln.BasicPullResponseHandler.onSuccess(BasicPullResponseHandler.java:119) ~[neo4j-java-driver-5.2.0.jar:5.2.0-e0e5b6a8d95e38084c5cf9ac39e3ee8c9f5f05d0]
        at org.neo4j.driver.internal.handlers.RoutingResponseHandler.onSuccess(RoutingResponseHandler.java:55) ~[neo4j-java-driver-5.2.0.jar:5.2.0-e0e5b6a8d95e38084c5cf9ac39e3ee8c9f5f05d0]
        at org.neo4j.driver.internal.async.inbound.InboundMessageDispatcher.handleSuccessMessage(InboundMessageDispatcher.java:87) ~[neo4j-java-driver-5.2.0.jar:5.2.0-e0e5b6a8d95e38084c5cf9ac39e3ee8c9f5f05d0]
        at org.neo4j.driver.internal.messaging.common.CommonMessageReader.unpackSuccessMessage(CommonMessageReader.java:68) ~[neo4j-java-driver-5.2.0.jar:5.2.0-e0e5b6a8d95e38084c5cf9ac39e3ee8c9f5f05d0]
        at org.neo4j.driver.internal.messaging.common.CommonMessageReader.read(CommonMessageReader.java:50) ~[neo4j-java-driver-5.2.0.jar:5.2.0-e0e5b6a8d95e38084c5cf9ac39e3ee8c9f5f05d0]
        at org.neo4j.driver.internal.async.inbound.InboundMessageHandler.channelRead0(InboundMessageHandler.java:81) ~[neo4j-java-driver-5.2.0.jar:5.2.0-e0e5b6a8d95e38084c5cf9ac39e3ee8c9f5f05d0]
        at org.neo4j.driver.internal.async.inbound.InboundMessageHandler.channelRead0(InboundMessageHandler.java:37) ~[neo4j-java-driver-5.2.0.jar:5.2.0-e0e5b6a8d95e38084c5cf9ac39e3ee8c9f5f05d0]
        at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:99) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:346) ~[netty-codec-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:318) ~[netty-codec-4.1.85.Final.jar:4.1.85.Final]
        at org.neo4j.driver.internal.async.inbound.MessageDecoder.channelRead(MessageDecoder.java:42) ~[neo4j-java-driver-5.2.0.jar:5.2.0-e0e5b6a8d95e38084c5cf9ac39e3ee8c9f5f05d0]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:346) ~[netty-codec-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:318) ~[netty-codec-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:286) ~[netty-handler-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:788) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:724) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:650) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562) ~[netty-transport-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[netty-common-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.85.Final.jar:4.1.85.Final]
        at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.85.Final.jar:4.1.85.Final]
        at java.base/java.lang.Thread.run(Thread.java:1589) ~[na:na]

Comment From: scottfrederick

This has also been reported at https://github.com/spring-projects/spring-data-neo4j/issues/2635.

Comment From: x-wing

Thanks for noting! Hope the attached project can help the investigation. Health endpoint is critical to our infrastructure which relies on the health status to automate deployments. This error gives a false signal.