The second release candidate of Home Assistant OS 18.4 went out on 23 October 2026 at 23:15 Polish time. Most of it is security housekeeping on top of RC1: Linux kernel 6.18.58, Buildroot 2025.02.19 and Go 1.27.3. The change worth testing is a fix for a common USB Bluetooth adapter, the Realtek RTL8761B with USB ID 0bda:a728, which the release notes say has been broken since kernel 6.18.45.
What the bug looked like
The problem was reported on 10 October in issue #5079. The adapter enumerated and loaded its firmware normally after boot, but a few hours later the kernel logged Bluetooth: hci0: command 0x200c tx timeout, reset the USB device and reloaded the firmware. Then it worked again until the next hang. The reporter ran HAOS as a virtual machine on Proxmox with the dongle passed through and used it for passive scanning with Bermuda.
The issue compares three builds on the same VM, adapter and firmware. On 18.2 with kernel 6.18.39 there were no timeouts over 2.69 days. On 18.3 with kernel 6.18.52 there were 28 in about three days, roughly nine a day, the first one about 5.5 hours after boot. A development build of 18.4 behaved the same way. In Home Assistant the hangs showed up as messages such as adapter 'hci0' not found and Adapter ... has moved to hci1, which means Bluetooth sensors and trackers went quiet each time. Rolling back to 18.2 made the problem go away.
This is a different issue from the RTL8761CU adapter that RC1 addressed by adding its firmware. That one never initialised at all. The RTL8761B loaded fine and failed later.
The fix
Pull request #5112, merged on 22 October, backports a patch that is in linux-next but has no stable kernel backport yet, adjusted for the 6.18 series. The release notes list it, along with the kernel update, for Home Assistant Green, the virtual appliance (OVA), generic x86-64, ODROID, Khadas VIM and generic aarch64. Raspberry Pi and Yellow images are not named in those notes.
Who gets it
RC2 is on the beta channel. On 24 October the stable channel still offered 18.3. If you own one of these dongles and have stayed on 18.2 because of the drop-outs, this release candidate is the build to try, either by switching to the beta channel or by waiting for 18.4 to reach stable.