server error 0 on Raspberry Pi Zero W

[sennluzi]

I have a Raspberry Pi Zero W v1.1. The flic button pairs perfectly on my Ubuntu machine. When I try to connect to it from my Raspberry Pi (arm version), scanning still works. But as soon as I try to connect to the button, the flicd-server outputs a "server error 0" and the client loses connection (InternetBackendError).

daemon-output:

$ sudo ./flicd -f server.db
Available HCI devices found:
hci0
Trying hci0
hci0 is busy, shutting down and retrying...
Successfully bound HCI socket
Flic server is now up and running!
Initialization of Bluetooth controller done!
Accepted new client
server error 0

simpleclient-output:

$ startScanWizard
Please click your Flic button!
Found private button. Please hold down it for 7 seconds to make it public.
Found public button 80:e4:da:74:db:88 F023dNuI, connecting...
Connected, now pairing and verifying...
Scan wizard done with status WizardInternetBackendError

or

$ scan
$ startScan
ADV: 80:e4:da:74:db:88 f023dNuI -72 private unverified
...
ADV: 80:e4:da:74:db:88 F023dNuI -95 public unverified
stopScan
connect 80:e4:da:74:db:88 64
Create conn: 64 NoError Disconnected
Connection status changed: 64 Connected
Connection status changed: 64 Disconnected Unspecified
Connection removed: 64 InternetBackendError