Hi,
Itś not a major bug, just a warning for people who encouter the same issue.
I use recently Tribler 6.2.0 on Linux Voyager X2 (Ubuntu) 14.04.
It works fine.
The last time I used a download directory on a USB stick and saved that choice in Preferences.
Now I started Tribler without the USB stick mounted so Tribler does not startup. After mounting the USB every worked fine.
And thanx for every bit of software which increases anomity for non criminal users.