java.lang.NoClassDefFoundError: Could not initialize class org.apache.jmeter.gui.util.MenuFactory

I’ve got a similar issue. The solution was changing the theme!

Try the following:

1. Open JMeter -> Options -> Look and Feel -> Select any other theme other than Darcula (E.g. System theme).
2. Restart JMeter.

source: https://www.javaer101.com/en/article/5555703.html