We've prepared firmware 126.96.36.19962. One really important point about this firmware is that there is downgrade protection for UAP-AC-HD/SHD (only). Once on 3.9.1, they will not be able to downgrade to earlier releases. You'll also notice that 1st gen AC firmware is no longer present. That's because they've moved to LTS support only. For more information on that, please seeHERE.
Please see below for the changelog and links to the firmware binaries.
Firmware changes from 3.8.12/14:**
[UAPG3] Add airView and airTime support for SHD.
[UAPG3] Add initial WIPS backend support for SHD.*
[UAPG3] Various HW accelerator fixes and improvements.
[UAPG3] Fixed issue with RF scan where it would often show 0% utilization.
[UAPG3] Fixed problem where uplink would stay in a disconnected state.
[UAPG3] Time it takes to provision has been reduced.
[UAPG3] Uplink / meshv3 improvements.
[UAPG3] General fixes and improvements (logging, wifi, and performance).
[UAPG3] Add LLDP support, which will improve PD negotiation on 3rd party swithes.
[UAPG3] Enable SHA512 support.
[UAP] Implement backend for SNMPv3 support.*
[UAP] Fix a RADIUS related bug with fast-apply.
[UAP] Numerous backend fixes and/or improvements.
[USL2] Fix PSU status detection.
[USW] Fix a bug preventing DHCPv6 from functioning in some cases.
[USW] Fix an issue with removing VLAN tags.
[USW] Fix an issue causing high CPU usage with some SFP modules.
[USW] Fix 802.1X VLAN setting on LAG groups.
[USW] Various backend fixes and/or improvements.
[HW] Merge with codename Toronto branch.
[HW] Add `do-upgrade` alias for local firmware upgrades.
Links are all HTTPS. This assumes your device(s) are currently running at least 3.7.51, and that the device's date is properly set (i.e. it can reach a NTP server). If you encounter issues with the upgrade, or your device isn't on a minimum supported firmware, then you can change the link to HTTP before performing the upgrade.