Internal error during buildout - Plone 5.2


seems like our buildout stops working on a Plone 5.2 installation. It worked fine the last weeks when we added several package to the [test] section of the develop.cfg file.

I stripped it down to referencing only one package in [test], but the following error occurs and i have no clue what is happening.

What would be the suggested steps to find out what is going wrong ? I guess a version change from a package in "the background". But which ?

Installing test.
  Installing test.

An internal error occurred due to a bug in either zc.buildout or in a
recipe being used:
Traceback (most recent call last):
  File "/opt/plone5.2/zinstance/lib/python3.8/site-packages/zc/buildout/", line 2174, in main
    getattr(buildout, command)(args)
  File "/opt/plone5.2/zinstance/lib/python3.8/site-packages/zc/buildout/", line 817, in install
    installed_files = self[part]._call(recipe.install)
  File "/opt/plone5.2/zinstance/lib/python3.8/site-packages/zc/buildout/", line 1603, in _call
    return f()
  File "/opt/plone5.2/buildout-cache/eggs/cp38/collective.xmltestreport-2.0.2-py3.8.egg/collective/xmltestreport/", line 42, in install
    eggs, ws = self.egg.working_set(
  File "/opt/plone5.2/buildout-cache/eggs/cp38/zc.recipe.egg-2.0.7-py3.8.egg/zc/recipe/egg/", line 78, in working_set
    ws = self._working_set(
  File "/opt/plone5.2/buildout-cache/eggs/cp38/zc.recipe.egg-2.0.7-py3.8.egg/zc/recipe/egg/", line 161, in _working_set
    ws = zc.buildout.easy_install.install(
  File "/opt/plone5.2/zinstance/lib/python3.8/site-packages/zc/buildout/", line 957, in install
    return installer.install(specs, working_set)
  File "/opt/plone5.2/zinstance/lib/python3.8/site-packages/zc/buildout/", line 673, in install
    requirements = [self._constrain(pkg_resources.Requirement.parse(spec))
  File "/opt/plone5.2/zinstance/lib/python3.8/site-packages/zc/buildout/", line 673, in <listcomp>
    requirements = [self._constrain(pkg_resources.Requirement.parse(spec))
  File "/opt/plone5.2/zinstance/lib/python3.8/site-packages/pkg_resources/", line 3148, in parse
    req, = parse_requirements(s)
ValueError: not enough values to unpack (expected 1, got 0)

develop.cfg [test] section is just

recipe = collective.xmltestreport
defaults = ['--auto-color', '--auto-progress', '--ignore_dir=.git', '--ignore_dir=bower_components', '--ignore_dir=node_modules' ]
eggs =

I found it out. For the records:

In the eggs-entries of a buildout.cfg you can comment out your packages with a '#'-mark.

When you do the same within the eggs-entries of the [test]-section in a develop.cfg and try to buildout -c develop.cfg to use it, the shown traceback is thrown.

So avoid to commented out egg-entries in the test-section of a develop.cfg

It happens to me a lot as well, but the problem is not adding a comment, but where the comment starts!

    # comment indented --> breaks buildout
# comment at the beginning --> buildout happily ignores it

At least that's my findings with this traceback :smile: