Although this is a dated bug report, I'm adding this note for others who might still encounter this bug.
I had the same Assertion 'kref' failed message when running some Qt 5.5.1 and Qt 5.6.0 webbrowser examples on Ubuntu 14.04 (32 bit). "nouveau" was the common factor. After much searching around and finally reading a clue about NVIDIA I launched Ubuntu Software Centre > Edit > Software Sources > Additional Drivers wait until all NVIDIA drivers are found and displayed .. NVIDIA Corporation: G86M [GeForce 8400M GS] Under NVIDIA there were 6 drivers listed: 5 proprietary, 1 open source. I was using .. X.Org X server - Nouveau display driver from xserver- xorg-video-nouveau (open source) I applied a different driver (the earliest NVIDIA proprietary version) NVIDIA legacy binary driver - version 173.14.39 from nvidia-173 (proprietary). Rebooted. The bootup screen might be different. I could then run the web browser apps in Qt Creator without nouveau crashing. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to webbrowser-app in Ubuntu. https://bugs.launchpad.net/bugs/1499419 Title: webbrowser-app: ../../nouveau/pushbuf.c:726: nouveau_pushbuf_data: Assertion `kref' failed. Status in webbrowser-app package in Ubuntu: New Bug description: webbrowser-app on Wily/unity8/mir/nouveau driver the browser crashes with webbrowser-app: ../../nouveau/pushbuf.c:726: nouveau_pushbuf_data: Assertion `kref' failed. nouveau: kernel rejected pushbuf: No such file or directory To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/webbrowser-app/+bug/1499419/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
