New "Starter Project" downloaded from Vaadin.com without modification fails

I go to:

https://vaadin.com/start/

I download either Vaadin 17 (pre-release) or Vaadin 16, with “Plain Java” option.

I open the project in IntelliJ 2020.2. I wait for Maven to catch-up with expanding the POM and downloading various things.

In IntelliJ I choose Build > Rebuild Project.

In IntelliJ, in the Maven panel, in the “Lifecycle” list, I run “clean” and “install”.

In IntelliJ, in the Maven panel, in the “Plugins” list, I run jetty:run.

I get this error:

Failed to execute goal org.eclipse.jetty:jetty-maven-plugin:9.4.28.v20200408:run (default-cli) on project bogus: Failure

Note that I made no modifications of any kind. Just download and run.

The only odd thing is that I am using Java 15 (pre-release, build 15+35-1559) installed on my Mac running Mojave 10.14.6. But I did not touch the POM file, so this is not running as a Java 15 executable.

I tried rebooting IntelliJ. I tried creating and running new projects repeatedly. I tried the IntelliJ menu item File > Invalidate caches / Restart. I tried deleting the .m2 folder, the cache for Maven. I am all out of tricks.

What magic incantations must I perform to get a new Vaadin project to run?

Hi Basil, I tried the same thing - downloaded Vaadin 17 Plain Java app, but ran

mvn -C clean package jetty:run

from the command-line instead. The app started properly for me; I’m running Java 8.

Could you please also try building/running the app from the command-line? Also could you try Java 11? Also please try running this from the command-line:

mvn -C -X jetty:run

That should log much more information.

Martin Vyšný:

Could you please also try building/running the app from the command-line? Also could you try Java 11? Also please try running this from the command-line:

Thanks for trying to help, but I do not have Maven installed, and never call it from the command-line. I don’t really want to start now.

I have always used Maven only from within IntelliJ. This has worked for me for many versions of Vaadin.

Is it really now necesary to use Maven outside of IntelliJ to get a default new project to run?

Hey Basil,

do I understand correctly that Java 15 pre-release is the only Java you have installed locally? Or does IntelliJ provide its own Java binaries. Can you check in your project setup please, which compiler is used exactly?

If it is Java 15 pre-release, there might be several causes:

  1. The Jetty you are using does not support some Java 15 feature, yet, and you will have to use a more recent version (I remember there was an issue like that in the past with Java 9).
  2. Our internal CI also noticed that builds of Flow itself with Java 15 fail. Might be an indicator for your issue, too.

Then, it would be good to get the full error log of your jetty:run and even better with debug output -X.

Cheers,
Paul