5 sourced reports, with what to check before you buy. Each one links to the page it was reported on.
Costly or dangerous
Hinge swivel damage is the most common Bose QC Ultra failure
A repair center's own repair data names hinge swivel damage as the most common QC Ultra failure, followed by hinge pins moving or falling out.
What to check. The hinge is a high-stress area; owners report it first feels loose, then cracks, then the swivel separates or the pin falls out and the ear cup dangles. Check hinge tightness early — once it loosens the damage accelerates, and repair/replacement is needed.
A German owner review reports the hinges crack loudly and calls it a design flaw, independently corroborating the hinge failure mode.
What to check. A second, independent owner report of hinge noise/cracking. If the hinges crack or feel loose, treat it as a structural issue rather than a cosmetic one.
QC Ultra fails to auto power off and drains battery
A German owner review reports the headphones fail to auto power off in 9 of 10 cases and run the battery down.
What to check. A second, independent report of the auto power-off fault, here manifesting as battery drain because the unit stays on. Expect to manage power manually or charge more often.
QC Ultra powers off during use despite 'never' auto-off setting
An owner reports the headphones switch off after ~10 minutes of inactivity even while worn, despite the 'never' auto-off setting, and that Bose support said it cannot be disabled.
What to check. If the unit powers down mid-use, the owner was advised this may be a hardware/battery or motion-sensor fault rather than a setting; check whether it correlates with low battery and use warranty while it lasts.
QC Ultra Bluetooth connection takes ~60 seconds with repeated reconnects on Linux
A user documents a ~60-second, multi-reconnect Bluetooth connection process on Linux, with repeated connect sounds and battery announcements before audio plays.
What to check. A Bluetooth-specific annoyance rather than a hardware failure: on some systems the QC Ultra takes ~60s and several reconnect cycles to deliver audio. Not fatal, but noticeable for daily use.
These reports come from the pages linked under each item: owner forums, repair guides and workshops. They are not a diagnosis of any one unit, and a careful check of the one you are buying still applies.
Text from the Kriko Over-ear noise-cancelling headphones catalog, version 0.1.1, under the CC-BY-SA-4.0 license.
