Starting Spring Boot application (Vaadin) stuck at running ‘npm install’

My Vaadin application used to work fine, but now when I want to start it the application is stuck at running npm install:

2022-10-02 15:24:49.482 INFO 27004 — [ main] dev-updater : Running npm install to resolve and optionally download frontend dependencies. This may take a moment, please stand by…

And I cant find a way to fix that.

Thanks in advance!

Answer

With npm install the first thing you can try is… wait. Sometimes it can be frustratingly slow. I have seen 10 minutes in extreme cases. It is especially slow if you have deleted package-lock.json or upgraded a lot of dependencies (like when you upgrade the Vaadin version).

Sometimes you can fix that by manually running npm install --prefer-offline once which will make npm spend less time looking for things to update and instead focus on installing the needed packages.

Overall if you run npm install manually once, you will better see progress and what is going on. You can even add the --verbose flag but that will probably give you more information than what you want.