Solved: SpringBoot startup error: Unable to start web server; nested exception is org.springframework.boot.web

error message

org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:161) ~[spring-boot-2.3.5.RELEASE.jar:2.3.5.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:545) ~[spring-context-5.2.10.RELEASE.jar:5.2.10.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:143) ~[spring-boot-2.3.5.RELEASE.jar:2.3.5.RELEASE]
    ......

Error reason

I checked some solutions, but finally found that this error was caused by: the jackson related package was referenced in the pom, but it was not completely referenced.

<dependency>
     <groupId>com.fasterxml.jackson.core</groupId>
     <artifactId>jackson-databind</artifactId>
     <version>2.13.3</version>
     <scope>compile</scope>
</dependency>

This Jackson is a widely used Java open source framework for serializing and deserializing json.

Solution: quote full dependencies

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
        <exclusions>
            <exclusion>
                <groupId>com.fasterxml.jackson.core</groupId>
                <artifactId>jackson-annotations</artifactId>
            </exclusion>
        </exclusions>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-annotations</artifactId>
    <version>2.9.8</version>
</dependency>