[java] Spring boot: Unable to start embedded Tomcat servlet container

I'm new to Spring Boot and having with error while running my application. I'm following a tutorial and I believe I'm having proper parent and dependencies with POM, please help me

main class:

package com.boot;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

/**
 * Hello world!
 *
 */

@SpringBootApplication
public class App 
{
    public static void main( String[] args )
    {
        SpringApplication.run(App.class, "hello");
    }
}

error is:

   org.springframework.boot.context.embedded.EmbeddedServletContainerException: Unable to start embedded Tomcat servlet container
        at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer.start(TomcatEmbeddedServletContainer.java:165) ~[spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
        at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.startEmbeddedServletContainer(EmbeddedWebApplicationContext.java:293) ~[spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
        at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.finishRefresh(EmbeddedWebApplicationContext.java:141) ~[spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:541) ~[spring-context-4.2.4.RELEASE.jar:4.2.4.RELEASE]
        at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:118) ~[spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:764) [spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
        at org.springframework.boot.SpringApplication.doRun(SpringApplication.java:357) [spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:305) [spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1124) [spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1113) [spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
        at com.boot.App.main(App.java:18) [classes/:na]Caused by: java.lang.IllegalStateException: Tomcat connector in failed state
        at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer.start(TomcatEmbeddedServletContainer.java:159) ~[spring-boot-1.3.1.RELEASE.jar:1.3.1.RELEASE]
        ... 10 common frames omitted

POM :

    <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.boot</groupId>
  <artifactId>das-boot</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.3.1.RELEASE</version>
    </parent>
  <name>das-boot</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
  <dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>

This could happen due to the change in java version of the project.Say for example if the project is build in java 8 and if we change the java version to 11 then there can be such issue. In intellij idea go to the File->Project Structure then change the Project SDK Version.

You need to Tomcat Dependency and also extend your Application Class from extends SpringBootServletInitializer

@SpringBootApplication  
public class App extend SpringBootServletInitializer
{
    public static void main( String[] args )
    {
        SpringApplication.run(App.class, "hello");
    }
}

For me, I just had to put a -X flag with mvn. Look at the debug log; there was an issue with Spring while locating the .properties file.

If you are running on a linux environment, basically your app does not have rights for the default port.

Try 8181 by giving the following option on VM.

-Dserver.port=8181

In my condition when I got an exception " Unable to start embedded Tomcat servlet container",

I opened the debug mode of spring boot by adding debug=true in the application.properties,

and then rerun the code ,and it told me that java.lang.NoSuchMethodError: javax.servlet.ServletContext.getVirtualServerName()Ljava/lang/String

Thus, we know that probably I'm using a servlet API of lower version, and it conflicts with spring boot version.

I went to my pom.xml, and found one of my dependencies is using servlet2.5, and I excluded it.

Now it works. Hope it helps.

For me, the problem was in XML migrations. I deleted all tables and sequences and it works on next bootRun

You need to add the tomcat dependency in your pom

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-tomcat</artifactId>
</dependency>

Simple way to handle this is to include this in your application.properties or .yml file: server.port=0 for application.properties and server.port: 0 for application.yml files. Of course need to be aware these may change depending on the springboot version you are using. These will allow your machine to dynamically allocate any free port available for use. To statically assign a port change the above to server.port = someportnumber. If running unix based OS you may want to check for zombie activities on the port in question and if possible kill it using fuser -k {theport}/tcp. Your .yml or .properties should look like this. server: port: 8089 servlet: context-path: /somecontextpath