Unbound on Raspberry Pi

[dy1977 at orange.fr]

Hello,

I developped an application around Unbound on a Rock64 SBC. This 
application uses a python script inside Unbound.

I tried to port it to the Raspberry Pi 3 (Raspbian Buster), but the 
loading of the python script fails with this error in syslog :

      notice: init module 0: validator
      notice: init module 1: python
      error: pythonmod: cannot initialize core module: unboundmodule.py
      error: module init for module python failed
      fatal error: failed to setup modules

The unboundmodule.py is present in /usr/lib/python3/dist-packages

What can I do to debug that ? I found no information of the nature of 
the problem.

I have verified all the imports, they are OK.

Thanks if you have an idea.

Dysmas

(France)