The dependencies of some of the beans in the application context form a cycle:

┌──->──┐

|  com.github.pagehelper.autoconfigure.PageHelperAutoConfiguration

└──<-──┘

Action:

Relying upon circular references is discouraged and they are prohibited by default. Update your application to remove the dependency cycle between beans. As a last resort, it may be possible to break the cycle automatically by setting spring.main.allow-circular-references to true.

springboot2.6.0版本和pagehelper-spring-boot-starter1.4.0有冲突：
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.6.0</version>  
</parent>
<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.4.0</version>
</dependency>
换一下版本就行。