Jetty SSL not working. Accessing website gives unreadable output - ssl

Question

EDIT: Self-signed certificate installed on browser made it work.
I have configured jetty 9 embedded for http on port 8080 and https on port 8443. When I visit localhost:8080 I get my website and everything works, but when I try to access localhost:8443, I get this mess: image of unreadable stuff.
I pretty much mimicked the ManyConnectorsExample in the jetty documentation in order to set up a http connector and a https connector. Here is my code:
File keystoreFile = new File("config/myownkeystore.p12");
if (!keystoreFile.exists()){
throw new FileNotFoundException(keystoreFile.getAbsolutePath());
}
Server server = new Server();
HttpConfiguration http_config = new HttpConfiguration();
http_config.setSecureScheme("https");
http_config.setSecurePort(8443);
http_config.setOutputBufferSize(32768);
ServerConnector http = new ServerConnector(server,
new HttpConnectionFactory(http_config));
http.setPort(8080);
http.setIdleTimeout(30000);
SslContextFactory sslContextFactory = new SslContextFactory();
sslContextFactory.setKeyStoreType("PKCS12");
sslContextFactory.setKeyStorePath(keystoreFile.getAbsolutePath());
sslContextFactory.setKeyStorePassword("myownstorepass");
sslContextFactory.setKeyManagerPassword("myownkeypass");
HttpConfiguration https_config = new HttpConfiguration(http_config);
SecureRequestCustomizer src = new SecureRequestCustomizer();
src.setStsMaxAge(2000);
src.setStsIncludeSubDomains(true);
https_config.addCustomizer(src);
ServerConnector https = new ServerConnector(server,
new SslConnectionFactory(sslContextFactory,HttpVersion.HTTP_1_1.asString()),
new HttpConnectionFactory(https_config));
https.setPort(8443);
https.setIdleTimeout(500000);
// Set the connectors
server.setConnectors(new Connector[] { http, https });
// servlet handler
ServletContextHandler servletContextHandler = new ServletContextHandler(ServletContextHandler.SESSIONS);
servletContextHandler.setResourceBase(".");
servletContextHandler.setContextPath("/");
servletContextHandler.addServlet(new ServletHolder(new MainServlet()), "/*");
// set the handlers
HandlerCollection handlerList = new HandlerCollection();
handlerList.setHandlers(new Handler[]{servletContextHandler});
server.setHandler(handlerList);
At first I thought that maybe the keystore type was at fault, since jetty uses jks by default. So I switched the sslcontext to use pkcs12 since the keystore is a .p12 file. That didn't help.
I checked the passwords next but the password for both private key and for the keystore are the same, so that can't be the issue.
At this point, I want to believe its a fault in my code somewhere, but I don't know what is wrong exactly.