Installtion problem with Arduino IDE for ESP32 under Ubunto

I am currently moving from the Windows IDE to Ubuntu. I ran into the following problem. When tying to compile a sketch and downloading it I get the following message
Traceback (most recent call last):

 File "/home/helmut/Arduino/hardware/espressif/esp32/tools/esptool/esptool.py", line 35, in <module>
    import serial.tools.list_ports as list_ports
ImportError: No module named serial.tools.list_ports
exit status 1
Fehler beim Kompilieren für das Board ESP32 Dev Module.

I found out that I have to use pip to install the python serial library which I did and which got me only one tiny step further:

Now I receive the following message which rather looks like a python installation problem than an arduino problem:

Traceback (most recent call last):
  File "/home/helmut/Arduino/hardware/espressif/esp32/tools/esptool/esptool.py", line 35, in <module>
    import serial.tools.list_ports as list_ports
  File "/usr/local/lib/python2.7/dist-packages/serial/__init__.py", line 27, in <module>
    from . import abc, model, marshal, errors, utilities, properties, meta, hooks, test, request  # noqa
  File "/usr/local/lib/python2.7/dist-packages/serial/model.py", line 44, in <module>
    from . import properties, meta, errors, hooks, abc
  File "/usr/local/lib/python2.7/dist-packages/serial/properties.py", line 34, in <module>
    from .abc.model import Model
ImportError: No module named abc.model
exit status 1
Fehler beim Kompilieren für das Board ESP32 Dev Module.

Now abc model is missing rather than th serial module. As far as I know this should be part of the indestinies of python 2.7.

Has anyone of you run into this problem and possibly managed to find a solution?
It would be very kind, if somebody had an idea how to fix this.

Thank you

Harry

Have you found a solution yet?