Failed to load widgets

Vaadin 6 / 7 / 8
1

i don’t understand anything.
i was doing the tutorial and all was going perfect.
in the middke of the stept 5
But now i can see anything in the browser except the mesage
Failed to load widgetset

¿Why does this error occurr?

2

Upss,
Now i did mvn wildfly:deploy in a console and now works…
i don’t understand anything
What has it happened with th e widgetset…

3

Now again appear the error failed to load widgetset,

It is so bizarre,

4

To sove it.
I have to do mvn clean.