PHPStorm cannot start browser - Ubuntu 18.04LTS Follow

I have a issue with PHP Storm in Ubuntu 18.04 LTS. I seems that the IDE cannot start the browser. So they neither start when I use the browser tollbar, the debuggin, nor the "Help->Contact Support" is working. I have already tried to disable all browsers except firefox (it is also the first in the line and the system feault). The path is simply "firefox". When I use "firefox" in a terminal window, the browser opens normally. Same result with chrome ("google-chrome").