I'm developing multiple sites on my local host using Symfony WebServer Bundle (so, the browser probably sees them as one, because the host is always 127.0.0.1:8000).
Now, I'm getting the session variables populated from another Contao installation in a completely new Contao project. In other words, it's the same session data across multiple local Contao installations. The data refer to extensions which are not installed, non-existing database columns etc. which leads to fatal errors of course.

How do I clear this session? What I tried so far:

- cache:clear (both prod and dev)
- manually deleting prod and dev cache folders
- clearing browser's cache
- manually clear browser's cookies
- manually deleting PHP session files from the directory in "session.save_path" ini setting
- restarting browser
- rebooting

What else do I miss here? Please help.