troubleshooting: add note on BlueZ GATT cache file
There is a bug (that has been recently fixed) in BlueZ where the GATT
cache was not removed when the device was removed, causing problems
for certain devices that change the attribute layout but don't support
the attribute database or services changed characteristics.
@@ -176,3 +176,9 @@ the device was connected. You can use the ``bluetoothctl`` command line tool to
.. code-block:: shell
bluetoothctl -- remove XX:XX:XX:XX:XX:XX
+ # prior to BlueZ 5.62 you also need to manually delete the GATT cache
+ sudo rm "/var/lib/bluetooth/YY:YY:YY:YY:YY:YY/cache/XX:XX:XX:XX:XX:XX"
+
+...where ``XX:XX:XX:XX:XX:XX`` is the Bluetooth address of your device and
+``YY:YY:YY:YY:YY:YY`` is the Bluetooth address of the Bluetooth adapter on
+your computer.
