spring-boot-starter-websocket : java.lang.ClassNotFoundException: reactor.netty.resources.LoopResources

[itboone]

I am using the spring-boot-starter-websocket with the version: 2.1.0.RELEASE.
I added the following dependencies as described in the documentation:

		<dependency>
			<groupId>io.projectreactor.ipc</groupId>
			<artifactId>reactor-netty</artifactId>
			<version>0.7.12.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>io.netty</groupId>
			<artifactId>netty-all</artifactId>
		</dependency>

BUT I got a error related to the netty when I startup , as follow:

org.springframework.context.ApplicationContextException: Failed to start bean 'stompBrokerRelayMessageHandler'; nested exception is java.lang.NoClassDefFoundError: reactor/netty/resources/LoopResources
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:185)
	at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:53)
	at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:360)
	at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:158)
	at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:122)
	at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:879)
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.finishRefresh(ServletWebServerApplicationContext.java:161)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549)
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140)
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775)
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:316)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248)
	at com.bo.msgpush.CloudMsgPushApplication.main(CloudMsgPushApplication.java:12)
Caused by: java.lang.NoClassDefFoundError: reactor/netty/resources/LoopResources
	at org.springframework.messaging.tcp.reactor.ReactorNettyTcpClient.<init>(ReactorNettyTcpClient.java:111)
	at org.springframework.messaging.simp.stomp.StompBrokerRelayMessageHandler.initTcpClient(StompBrokerRelayMessageHandler.java:435)
	at org.springframework.messaging.simp.stomp.StompBrokerRelayMessageHandler.startInternal(StompBrokerRelayMessageHandler.java:401)
	at org.springframework.messaging.simp.broker.AbstractBrokerMessageHandler.start(AbstractBrokerMessageHandler.java:186)
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:182)
	... 14 common frames omitted
Caused by: java.lang.ClassNotFoundException: reactor.netty.resources.LoopResources
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:338)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	... 19 common frames omitted

Notice

I got this problem as I upgrade the version 2.0.3.RELEASE to 2.1.0.RELEASE. I have running the project well in the old version, so I think there is some error with the version 2.1.0.RELEASE.

My config:

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {

  @Override
  public void configureMessageBroker(MessageBrokerRegistry config) {
    config.enableStompBrokerRelay("/topic").setRelayHost("localhost");
    config.setApplicationDestinationPrefixes("/app");
  }

  @Override
  public void registerStompEndpoints(StompEndpointRegistry registry) {
    registry.addEndpoint("/test").withSockJS();
  }
}

My pom:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>com.bo</groupId>
	<artifactId>cloud_msg_push</artifactId>
	<version>0.0.1</version>
	<packaging>jar</packaging>

	<name>cloud_msg_push</name>
	<description>demo for spring cloud</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.0.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
		<spring-cloud.version>Finchley.RELEASE</spring-cloud.version>
		<skipTests>true</skipTests>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-redis</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-thymeleaf</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-config</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-amqp</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-websocket</artifactId>
		</dependency>
		<dependency>
			<groupId>io.projectreactor.ipc</groupId>
			<artifactId>reactor-netty</artifactId>
			<version>0.7.12.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>io.netty</groupId>
			<artifactId>netty-all</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-aop</artifactId>
		</dependency>
		<dependency>
			<groupId>com.google.code.gson</groupId>
			<artifactId>gson</artifactId>
		</dependency>
		<dependency>
			<groupId>org.apache.commons</groupId>
			<artifactId>commons-lang3</artifactId>
		</dependency>
		<dependency>
			<groupId>org.apache.httpcomponents</groupId>
			<artifactId>httpclient</artifactId>
		</dependency>
		
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		
		<dependency>
			<groupId>com.bo.common</groupId>
			<artifactId>common-utils</artifactId>
			<version>1.0</version>
			<scope>system</scope>
			<systemPath>${basedir}/lib/common-utils-1.0.jar</systemPath>
		</dependency>
	</dependencies>

	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>org.springframework.cloud</groupId>
				<artifactId>spring-cloud-dependencies</artifactId>
				<version>${spring-cloud.version}</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
				<configuration>
					<includeSystemScope>true</includeSystemScope>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>

[spencergibb]

Spring cloud Finchley is not compatible with boot 2.1.x

[wilkinsona]

Furthermore, you have hardcoded the version of Reactor Netty rather than relying on Spring Boot's dependency management. As a result, the versions are incompatible.

If you have any follow-up questions, please ask on Stack Overflow or Gitter. As mentioned in the guidelines for contributing, we prefer to use GitHub issues only for bugs and enhancements.

[spencergibb]

The groupId for reactor-netty also changed to io.projectreactor.netty from io.projectreactor.ipc.