Install opensesame on ubuntu with anaconda

Hi everyone,

I'm currently struggling to install opensesame on ubuntu using anaconda, and I don't understand the error message I have. You will find below the error message, what I've done so far and all the packages currently installed.

Error message :
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/volatile/opt/anaconda3/envs/opensesame-py3/lib/python3.7/multiprocessing/spawn.py", line 105, in spawn_main
exitcode = _main(fd)
File "/volatile/opt/anaconda3/envs/opensesame-py3/lib/python3.7/multiprocessing/spawn.py", line 114, in _main
prepare(preparation_data)
File "/volatile/opt/anaconda3/envs/opensesame-py3/lib/python3.7/multiprocessing/spawn.py", line 225, in prepare
_fixup_main_from_path(data['init_main_from_path'])
File "/volatile/opt/anaconda3/envs/opensesame-py3/lib/python3.7/multiprocessing/spawn.py", line 277, in _fixup_main_from_path
run_name="__mp_main__")
File "/volatile/opt/anaconda3/envs/opensesame-py3/lib/python3.7/runpy.py", line 263, in run_path
pkg_name=pkg_name, script_name=fname)
File "/volatile/opt/anaconda3/envs/opensesame-py3/lib/python3.7/runpy.py", line 96, in _run_module_code
mod_name, mod_spec, pkg_name, script_name)
File "/volatile/opt/anaconda3/envs/opensesame-py3/lib/python3.7/runpy.py", line 85, in _run_code
exec(code, run_globals)
File "/volatile/opt/anaconda3/envs/opensesame-py3/bin/opensesame", line 6, in <module>
from libqtopensesame.__main__ import opensesame
File "/volatile/opt/anaconda3/envs/opensesame-py3/lib/python3.7/site-packages/libqtopensesame/__main__.py", line 29, in <module>
multiprocessing.set_start_method('spawn')
File "/volatile/opt/anaconda3/envs/opensesame-py3/lib/python3.7/multiprocessing/context.py", line 242, in set_start_method
raise RuntimeError('context has already been set')
RuntimeError: context has already been set

So here is what I've done so far (followed the download instructions from this page https://osdoc.cogsci.nl/3.3/download/, and ran some other lines after seeing the errors) :

conda create -n opensesame-py3 python=3.7
conda activate opensesame-py3
conda config --add channels cogsci --add channels conda-forge
conda install python-opensesame opensesame-extension-osweb opensesame-plugin-psychopy psychopy rapunzel python-pygaze
pip install soundfile pygame yolk3k opensesame-extension-osf python-qtpip http://files.cogsci.nl/expyriment-0.10.0+opensesame2-py3-none-any.whl
conda install PyQtWebEngine
conda install jupyter_client==7.4.4
pip install opensesame-plugin-media_player_mpy

I don't see what I'm doing wrong ?

Thank you so much in advance for your help

Julia