最新版本的Spring需要reactor 2.0，看看你的POM有一个明确的1.1.6依赖。
解决：
<dependency>
<groupId>org.projectreactor</groupId>
<artifactId>reactor-core</artifactId>
<version>1.1.6.RELEASE</version>
</dependency> <dependency>
<groupId>org.projectreactor</groupId>
<artifactId>reactor-net</artifactId>
<version>1.1.6.RELEASE</version>
</dependency> <dependency>
<groupId>org.projectreactor</groupId>
<artifactId>reactor-tcp</artifactId>
<version>1.0.1.RELEASE</version>
</dependency> <dependency>
<groupId>org.projectreactor</groupId>
<artifactId>reactor-spring</artifactId>
<version>1.0.1.RELEASE</version>
</dependency>