Blutooth connection

[Kira-78963]

my bluetooth device is not connecting to my pc
trowing the error
br-connection-key-missing

[JJ-coder-snow]

my bluetooth device is not connecting to my pc
trowing the error
br-connection-key-missing

[Mespique]

Same error "br-connection-key-missing" in blueman, for a Sennheiser Momentum 4 headset. Issue started today february 2nd 2026.
I've got another set of headphones "hoomband" that is not discovered at all either by bluman or bluetoothctl scan on. It used to be as off february 1st 2026.

I'm running bluman-manager 2.4.6 on Garuda Linux

"bluetoothctl scan on" returns:
[CHG] Device 80:C3:BA:9A:8E:FF Connected: yes
[SIGNAL] BREDR.Disconnected - org.bluez.Reason.Remote, Connection terminated by remote user
[SIGNAL] Disconnected - org.bluez.Reason.Remote, Connection terminated by remote user
[CHG] Device 80:C3:BA:9A:8E:FF Connected: no

"bluetoothctl pair 80:C3:BA:9A:8E:FF" returns
Attempting to pair with 80:C3:BA:9A:8E:FF
[CHG] Device 80:C3:BA:9A:8E:FF Connected: yes
Failed to pair: org.bluez.Error.AuthenticationFailed
[SIGNAL] BREDR.Disconnected - org.bluez.Reason.Local, Connection terminated by local host
[SIGNAL] Disconnected - org.bluez.Reason.Local, Connection terminated by local host
[CHG] Device 80:C3:BA:9A:8E:FF Connected: no

var/lib/blueman/ contains network.state that is mostly unreadable (bad or weird encoding?)
nanoing it returns:

�^Bcblueman.main.NetConf
NetConf
q^@)�q^A}q^B(X^H^@^@^@ip4_maskq^CNX^K^@^@^@ip4_addressq^DNX^G^@^@^@versionq^EK
X^L^@^@^@dhcp_handlerq^FNX ^@^@^@ipt_rulesq^G]q^HX^K^@^@^@ip4_changedq �ub.

var/lib/bluetooth is empty.

I have no idea how to manually authenticate the headphones, there's no way to input anything and it obviously cannot tell me its key.

I've tried the obvious: removing and rediscovering the device. It doesn't work.

I should add that I'm able to connect BOSE 700 NC headphones without issue.

[Mespique]

If anyone found this discussion through a search engine, like I did, here's how I solved it today:

For the Hoomband: I connected via Bluetooth to a windows PC. Then on my linux laptop blueman was able to correctly discover, pair and connect to it.

For the Sennheiser's Momentum 4: I connected it to my phone through the official app. From there I deleted my PC from the headphones' internal memory. Then it again became pairable & connectable to my linux laptop.