ZopeXMLConfigurationError. How to check out CMFPlone

I updated a 6.0.0.xy from packages installation to 6.0.3.

Now runwsgi instance/etc/zope.ini fails with stumbling about
<five:loadProducts file="meta.zcml"/>

Any hint, what needs to be adapted?
Thanks!

 source venv/bin/activate; runwsgi instance/etc/zope.ini                                                 
Traceback (most recent call last):
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/zope/configuration/xmlconfig.py", line 393, in endElementNS
    self.context.end()
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/zope/configuration/config.py", line 703, in end
    self.stack.pop().finish()
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/zope/configuration/config.py", line 873, in finish
    actions = self.handler(context, **args)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/OFS/metaconfigure.py", line 45, in loadProducts
    zcml = os.path.join(os.path.dirname(product.__file__), file)
  File "/Users/katjasuss/.pyenv/versions/3.9.10/lib/python3.9/posixpath.py", line 152, in dirname
    p = os.fspath(p)
TypeError: expected str, bytes or os.PathLike object, not NoneType

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/katjasuss/Volto/BACKEND/venv/bin/runwsgi", line 8, in <module>
    sys.exit(main())
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/Zope2/Startup/serve.py", line 251, in main
    return command.run()
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/Zope2/Startup/serve.py", line 189, in run
    app = self.loadapp(app_spec, name=app_name, relative_to=base,
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/Zope2/Startup/serve.py", line 220, in loadapp
    return loadapp(app_spec, name=name, relative_to=relative_to, **kw)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/paste/deploy/loadwsgi.py", line 248, in loadapp
    return loadobj(APP, uri, name=name, **kw)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/paste/deploy/loadwsgi.py", line 273, in loadobj
    return context.create()
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/paste/deploy/loadwsgi.py", line 741, in create
    return self.object_type.invoke(self)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/paste/deploy/loadwsgi.py", line 200, in invoke
    app = context.app_context.create()
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/paste/deploy/loadwsgi.py", line 741, in create
    return self.object_type.invoke(self)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/paste/deploy/loadwsgi.py", line 138, in invoke
    return fix_call(context.object, context.global_conf, **context.local_conf)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/paste/deploy/util.py", line 61, in fix_call
    val = callable(*args, **kw)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/Zope2/Startup/run.py", line 61, in make_wsgi_app
    starter.prepare()
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/Zope2/Startup/starter.py", line 38, in prepare
    self.startZope()
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/Zope2/Startup/starter.py", line 94, in startZope
    Zope2.startup_wsgi()
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/Zope2/__init__.py", line 36, in startup_wsgi
    _startup()
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/Zope2/App/startup.py", line 126, in startup
    load_zcml()
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/Zope2/App/startup.py", line 41, in load_zcml
    load_site()
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/Zope2/App/zcml.py", line 45, in load_site
    _context = xmlconfig.file(site_zcml)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/zope/configuration/xmlconfig.py", line 663, in file
    include(context, name, package)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/zope/configuration/xmlconfig.py", line 560, in include
    processxmlfile(f, context)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/zope/configuration/xmlconfig.py", line 409, in processxmlfile
    parser.parse(src)
  File "/Users/katjasuss/.pyenv/versions/3.9.10/lib/python3.9/xml/sax/expatreader.py", line 111, in parse
    xmlreader.IncrementalParser.parse(self, source)
  File "/Users/katjasuss/.pyenv/versions/3.9.10/lib/python3.9/xml/sax/xmlreader.py", line 125, in parse
    self.feed(buffer)
  File "/Users/katjasuss/.pyenv/versions/3.9.10/lib/python3.9/xml/sax/expatreader.py", line 217, in feed
    self._parser.Parse(data, isFinal)
  File "/private/var/folders/jp/b_42_w2s5ss_m87wcrktdp380000gn/T/python-build.20220116102819.4916/Python-3.9.10/Modules/pyexpat.c", line 461, in EndElement
  File "/Users/katjasuss/.pyenv/versions/3.9.10/lib/python3.9/xml/sax/expatreader.py", line 381, in end_element_ns
    self._cont_handler.endElementNS(pair, None)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/zope/configuration/xmlconfig.py", line 395, in endElementNS
    self._handle_exception(ex, info)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/zope/configuration/xmlconfig.py", line 237, in _handle_exception
    reraise(exc, None, sys.exc_info()[2])
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/zope/configuration/_compat.py", line 31, in reraise
    raise value.with_traceback(tb)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/zope/configuration/xmlconfig.py", line 393, in endElementNS
    self.context.end()
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/zope/configuration/config.py", line 703, in end
    self.stack.pop().finish()
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/zope/configuration/config.py", line 873, in finish
    actions = self.handler(context, **args)
  File "/Users/katjasuss/Volto/BACKEND/venv/lib/python3.9/site-packages/OFS/metaconfigure.py", line 45, in loadProducts
    zcml = os.path.join(os.path.dirname(product.__file__), file)
  File "/Users/katjasuss/.pyenv/versions/3.9.10/lib/python3.9/posixpath.py", line 152, in dirname
    p = os.fspath(p)
zope.configuration.xmlconfig.ZopeXMLConfigurationError: File "/Users/katjasuss/Volto/BACKEND/instance/etc/site.zcml", line 14.2-14.39
    TypeError: expected str, bytes or os.PathLike object, not NoneType

[EDIT]
I checked out CMFPlone

"mx.ini":

[Products.CMFPlone]
url=git@github.com:plone/Products.CMFPlone.git
branch = master

is this file empty or malformed?