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Java Intro to Java Web Development with Spark Bells and Whistles Accessing Specific Items

503 Internal Error

I have no idea what is up with my spark app. I added the two extra dependencies to my gradle file in hope that it would give me a bit more information:

    compile "org.slf4j:slf4j-simple:1.7.21"
    compile "org.slf4j:slf4j-api:1.7.21"

But once I hit the 503 Internal Error I get no additional information that Craig seems to be getting in this series when he comes across an error. My files look like so:


//... imports and package declaration omitted

public class Main
    public static void main(String[] args) {

        CourseIdeaDAO dao = new SimpleCourseIdeaDAO();


        before((request, response) -> {
            if (request.cookie("username") != null) {
                request.attribute("username", request.cookie("username"));

        before("/ideas", ((request, response) -> {
            // TODO:pjh - send message about redirect somehow
            if (request.cookie("username") == null) {

        // ... other methods omitted from this forum

        get("/ideas", (request, response) -> {
            Map<String, Object> model = new HashMap<>();
            model.put("ideas", dao.findAll());
            return new ModelAndView(model, "ideas.hbs");
        }, new HandlebarsTemplateEngine());

        post("/ideas", (request, response) -> {
            String title = request.queryParams("title");
            // TODO:pjh - This username is tied to the cookie implementation
            CourseIdea courseIdea = new CourseIdea(title, request.cookie("username"));
            return null;



public class CourseIdea {
    private String slug;
    private String title;
    private String creator;
    private Set<String> voters;

    public CourseIdea(String title, String creator) {
        this.title = title;
        this.creator = creator;

        Slugify slugify = new Slugify();
        slug = slugify.slugify(title);


    public String getTitle() {
        return title;

    public String getCreator() {
        return creator;

    public String getSlug() { return slug; }

    public boolean addVoter(String voterUserName) {
        return voters.add(voterUserName);

    public int getVoteCount() {
        return voters.size();

    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        CourseIdea that = (CourseIdea) o;

        if (title != null ? !title.equals(that.title) : that.title != null) return false;
        return creator != null ? creator.equals(that.creator) : that.creator == null;


    public int hashCode() {
        int result = title != null ? title.hashCode() : 0;
        result = 31 * result + (creator != null ? creator.hashCode() : 0);
        return result;


public class SimpleCourseIdeaDAO implements CourseIdeaDAO {

    private List<CourseIdea> ideas;

    public SimpleCourseIdeaDAO() {
        ideas = new ArrayList<>();

    public boolean add(CourseIdea course) {
        return ideas.add(course);

    public List<CourseIdea> findAll() {
        return new ArrayList<>(ideas);

    public CourseIdea findBySlug(String slug) {
        return ideas.stream()
                .filter(idea -> idea.getSlug().equals(slug))


Does anybody know why I would be receiving a 503 error? Have I set up my configuration wrongly?

2 Answers

Alexander Nikiforov
.a{fill-rule:evenodd;}techdegree seal-36
Alexander Nikiforov
Java Web Development Techdegree Graduate 22,161 Points

It definitely does not have to do with your java files.

The best way to help you would be that you push your project on GitHub with ALL files. This is very important.

Then I can try to clone it and reproduce error.

You should also see errors in your console: something like that:

[Thread-0] INFO org.eclipse.jetty.util.log - Logging initialized @404ms
[Thread-0] INFO spark.webserver.JettySparkServer - == Spark has ignited ...
[Thread-0] INFO spark.webserver.JettySparkServer - >> Listening on
[Thread-0] INFO org.eclipse.jetty.server.Server - jetty-9.3.2.v20150730
[Thread-0] INFO org.eclipse.jetty.server.ServerConnector - Started ServerConnector@73443c5b{HTTP/1.1,[http/1.1]}{}
[Thread-0] INFO org.eclipse.jetty.server.Server - Started @709ms

When it is a 503 error, stack trace should be printed in console.

Please attach this info as well.

One more question would be, does your App run?

What I mean by that does Spark start, and you see that App is running, or it does not?

The thing you also should do, or at least I would've done, is to clone Craigs original project:


add your slfj dependencies and change sourceCompatibility in build.gradle file

group 'com.teamtreehouse.courses'
version '1.0-SNAPSHOT'

apply plugin: 'java'

sourceCompatibility = 1.8

repositories {

dependencies {
    compile 'com.sparkjava:spark-core:2.3'
    compile 'com.sparkjava:spark-template-handlebars:2.3'
    compile 'com.github.slugify:slugify:2.1.4'
    compile "org.slf4j:slf4j-simple:1.7.21"
    compile "org.slf4j:slf4j-api:1.7.21"
    testCompile group: 'junit', name: 'junit', version: '4.11'

The app should work 100 % no 503 errors.

If it does not work, may be you somehow set up your gradle incorrectly. Then I would have checked 'introduction to Gradle` to make sure all dependencies work.

It may also be that port is busy that you are running your app into

Why do you set it to


Is there a reason for that ?

It's weird, once I downgraded spark from 2.5 to 2.3 the error messages started showing up, and you were right about it not being a Java error. It was a handlebars error. Possibly something that hasn't been fully patched here:


Thanks for your help!