Vaadin Start changing theme to Material

I created a project using Vaadin Start with the Lumo Dark theme.
The Application class is annotated with @Theme(value = “myproject”, variant = Lumo.DARK)
Everything worked fine.
Then i wanted to change the theme to the Material Dark theme.
I changed it to @Theme(value = “myproject”, themeClass = Material.class, variant = Material.DARK)
Now the page is stuck at loading

When i click at the Red ! at the bottom it says
NotSupportedError: Failed to execute ‘define’ on ‘CustomElementRegistry’: the name “vaadin-material-styles” has already been used with this registry

You can’t create your own theme based on material

I dont get it

How can i change it then to Material?

As far as I know, remove your theme folder from the frontend and remove the value of the annotation

Deleted the theme and changed it to @Theme(themeClass = Material.class, variant = Material.DARK)

still doesnt work

Did you had the app running beforehand with Lumo?

Could be caused by


In the linked issue is a workaround by Artur



there is a soulution I asked same question months ago