Plone 6 & ZEO: instances are not starting

I'm trying to run Plone 6 with ZEO but the instances are not starting and I get the following error:

Traceback (most recent call last):
  File "/tmp/test_plone/./bin/client1", line 283, in <module>
  File "/tmp/buildout-cache/eggs/plone.recipe.zope2instance-6.11.0-py3.9.egg/plone/recipe/zope2instance/", line 1038, in main
    c.onecmd(" ".join(options.args))
  File "/usr/lib/python3.9/", line 217, in onecmd
    return func(arg)
  File "/tmp/buildout-cache/eggs/zdaemon-4.3-py3.9-linux-x86_64.egg/zdaemon/", line 554, in do_fg
  File "/tmp/buildout-cache/eggs/plone.recipe.zope2instance-6.11.0-py3.9.egg/plone/recipe/zope2instance/", line 860, in do_foreground
    self._exitstatus =, env=env)
  File "/usr/lib/python3.9/", line 349, in call
    with Popen(*popenargs, **kwargs) as p:
  File "/usr/lib/python3.9/", line 951, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/usr/lib/python3.9/", line 1754, in _execute_child = _posixsubprocess.fork_exec(
TypeError: expected str, bytes or os.PathLike object, not NoneType

The instance is configured with buildout and venv.

Can anyone help me?


Hi! which python version and how did you install Plone?

I'm using python 3.9.

I'm using buildout to configure and install Plone.