Unable to start embedded Tomcat using NetBeans 8.2 and Spring Boot

Question

Can anyone advise why a Spring Boot application, which has worked well in the past, is suddenly unable to start embedded Tomcat?

Project dependencies are:

<dependencies>
        <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.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

And I am using JDK8 in NetBeans 8.2 trying to connect to Apache Derby.

I have tried several of the options described in similar questions like Spring boot: Unable to start embedded Tomcat servlet container but I simply get the message about being unable to start Tomcat. The project works on another PC so the cause may be environmental. The stacktrace is:

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:155) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:544) ~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at com.city2018.webapps.code.LibraryWithThymeleafDatabaseApplication.main(LibraryWithThymeleafDatabaseApplication.java:20) [classes/:na]
Caused by: org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
    at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:126) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.<init>(TomcatWebServer.java:86) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getTomcatWebServer(TomcatServletWebServerFactory.java:409) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getWebServer(TomcatServletWebServerFactory.java:174) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:179) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:152) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    ... 8 common frames omitted
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardServer[-1]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.startup.Tomcat.start(Tomcat.java:367) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:107) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
    ... 13 common frames omitted
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardService[Tomcat]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:793) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    ... 15 common frames omitted
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Tomcat]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:422) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    ... 17 common frames omitted
Caused by: org.apache.catalina.LifecycleException: A child container failed during start
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:949) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    ... 19 common frames omitted

Have you verified that none of the ports you need are already in use? If so then you could set **debug=true** in your **application.properties** of your Spring Boot application to see if that yields something more meaningful than your stack trace. — skomisa, Oct 08 '18 at 18:17
Thanks to the respondents. It is quote possible that another application is using port 8080. So I will have to try another port. — Mr Morgan, Oct 08 '18 at 21:25

Mr Morgan · Answer 1 · 2018-10-10T23:01:42.887

0

This problem was to do with universal naming convention (UNC) paths, e.g. \\servername\path, in the NetBeans settings of the project I am using. The copy of the project which ran successfully did not use a UNC path, rather it identified a drive letter. So I changed the settings in the project causing problems and everything works normally.

I could simply delete this question, but perhaps this answer will be of use to someone.

edited Oct 10 '18 at 23:01

answered Oct 09 '18 at 22:02

Mr Morgan

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But does that explain why your application suddenly stopped working, or continued to run successfully from another machine? – skomisa Oct 10 '18 at 22:20
The text of answer has been revised. – Mr Morgan Oct 10 '18 at 22:53
OK, now it all makes sense. Don't delete this. – skomisa Oct 10 '18 at 22:59
I will not be deleting the question/answer now. – Mr Morgan Oct 10 '18 at 23:00

Unable to start embedded Tomcat using NetBeans 8.2 and Spring Boot

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