Failed to start with the QtWebEngine backend!

qutebrowser tried to start with the QtWebEngine backend but failed because you're using Nouveau graphics.

There aer two ways to fix this:

Forcing software rendering

This allows you to use the newer QtWebEngine backend (based on Chromium) but could have noticeable performance impact (depending on your hardware). This sets the qt.force_software_rendering = True options (if you have a config.py file, you'll need to set thsi manually).

Forcing the QtWebket backend
This forces usage of the QtWebkit backend by setting the backend = 'webkit' option (if you have a config.py file, you'll need to set this manually).