HTC is now rolling out Android 8.0 Oreo with the new software update 2.31.400.6 for HTC U11 smartphones. New features like Parallel Apps, Auto-fill, Picture-in-Picture, Smart text selection, new design for Quick Settings, and other features.
In addition, the update comes with latest Android Security patch with brings fixes for Common Vulnerabilities and Exposures discovered in the Android operating system. The firmware update also includes device stability improvements, bug fixes and further improvements for performance.
Software update 2.31.400.6 for HTC U11 smartphones will gradually release to everyone. You can also check manually for updates, go to Settings > About device > System update.
Make sure you have enough charge on your device at least 60% to 70% before downloading the update.