I am new to all of this, but I installed java jdk-11.0.2, Eclipse 2018-12 and installed Vaadin via the Eclipse Marketplace. When I go into the Vaadin perspective I get the message “A palette is not available.” in the Palette window. I had installed Vaadin in an old version of Eclipse and all was working fine.
This is a known issue. Eclipse 2018-12 is not recognized by the newest version of the plugin, so you get the old one from Marketplace causing this issue. There is ticket here:
https://github.com/vaadin/eclipse-plugin/issues/755
See also comment:
“Workaround for this is to manually add link http://vaadin.com/eclipse/ to “Install new software…” window in Eclipse. After that you can install the latest version of plugin from it.”