Characteristic value/descriptor read failed: Invalid handle

[MennoLabs]

I had to add #! /usr/bin/python3 to the script to get it to execute at all.

Now I am getting:
./domoticz_mijia.py
./domoticz_mijia.py:24: DeprecationWarning: encodestring() is a deprecated alias since 3.1, use encodebytes()
base64string = base64.encodestring(('%s:%s' % (domoticzusername, domoticzpassword)).encode()).decode().replace('\n', '')

1: updating
Characteristic value/descriptor read failed: Invalid handle
Characteristic value/descriptor read failed: Invalid handle
Characteristic value/descriptor read failed: Invalid handle
Characteristic value/descriptor read failed: Invalid handle
Error reading value retry after 5 seconds...

Changing encodestring to encodebytes gets rid of the deprecation warning, but nets the same consecutive errors.