Plone 5.2.8 released

I have released Plone 5.2.8.
With Buildout you can use the versions file at
With pip you can use the constraints file at

See the release page on for more info and links to the installers.

Please read the information below about waitress carefully.

Interesting changes since 5.2.7:

  • Zope: Enhance cookie support. For details, see issue 1010
    For more changes see Change log — Zope documentation 4.6 documentation
  • waitress is updated to version 2.1.1 to mitigate a vulnerability in that package. As waitress no longer supports Python versions less than 3.7 it is not advised to run Plone 5.2 on Python 2.7 or 3.6 any longer, even though they are still supported by Plone itself. You get an older waitress version then. If you must use an old Python version, please switch to a different WSGI server. See the recommendations in the Zope documentation.
  • WARNING: the new waitress 2.1.1 does seem to suffer from a possible race condition leading to the process quitting. If you are affected by this, you can downgrade to 2.1.0 (which has a known security vulnerability, as mentioned above) or use a different WSGI server.
  • Track link integrity of referenced PDFs and other site objects in IFRAME SRC references.
  • plone.outputfilters: Resolve UIDs in SRC attribute of of SOURCE and IFRAME elements.
  • Add lazy attribute to vocabularies to prevent fetching any results.
  • plone.schema: Use indent in json.dumps to make JSON readable in the widget.
1 Like

Thanks! now runs on 5.2.8

1 Like

Docker image plone/plone-backend also released

Just updated to 5.2.8 look fine, thanks.

About waitress I still see errors with 2.1.1 from time to time. They should be solved in waitress 2.1.2 released yesterday.

I made a PR in Update waitress to version 2.1.2 by ale-rt · Pull Request #1046 · zopefoundation/Zope · GitHub and I am testing 2.1.2 in some of my projects.

1 Like

Is anyone else seeing problems with waitress 2.1.1?

I have got "OSError: [Errno 9] Bad file descriptor" while testing Plone 5.2.8.

Is there a reason not to use waitress 2.1.2?

I cannot tell from this short error message if this is related to waitress.
It should be fine to use the newer version though. If that unexpectedly gives more problems, you can easily revert.

Thank you for the quick reply
Yes, it is waitress related and "Bad FileDescriptor" is the same error as mentioned at

AttributeError: 'NoneType' object has no attribute 'sync'
    exec(compile(, __file__, "exec"))
  File "/buildout-cache/eggs/Zope-4.8.1-py3.7.egg/Zope2/Startup/", line 255, in <module>
    sys.exit(main() or 0)
  File "/buildout-cache/eggs/Zope-4.8.1-py3.7.egg/Zope2/Startup/", line 251, in main
  File "/buildout-cache/eggs/Zope-4.8.1-py3.7.egg/Zope2/Startup/", line 217, in run
  File "/buildout-cache/eggs/Zope-4.8.1-py3.7.egg/Zope2/Startup/", line 203, in serve
  File "/buildout-cache/eggs/plone.recipe.zope2instance-6.11.0-py3.7.egg/plone/recipe/zope2instance/", line 942, in serve
    return serve_paste(app, global_conf, **kws)
  File "/buildout-cache/eggs/plone.recipe.zope2instance-6.11.0-py3.7.egg/plone/recipe/zope2instance/", line 917, in serve_paste
    waitress.serve(app, **kw)
  File "/buildout-cache/eggs/waitress-2.1.1-py3.7.egg/waitress/", line 19, in serve
  File "/buildout-cache/eggs/waitress-2.1.1-py3.7.egg/waitress/", line 325, in run
  File "/buildout-cache/eggs/waitress-2.1.1-py3.7.egg/waitress/", line 245, in loop
    poll_fun(timeout, map)
  File "/buildout-cache/eggs/waitress-2.1.1-py3.7.egg/waitress/", line 172, in poll
    r, w, e =, w, e, timeout)
OSError: [Errno 9] Bad file descriptor

I will pin waitress to 2.1.2.

1 Like

I can confirm this error in Plone 5.2.8. Zope 4.8.2 pinned waitress = 2.1.2, which fixes this error:

So a version of Plone with Zope 4.8.2 is welcome!


I can confirm too in Plone 5.2.8 pinning waitress = 2.1.2 fixes the Bad file descriptor error. But Client disconnected while serving is still an issue. See Waitress "Client disconnected while serving" and "Bad file descriptor".