AttributeError: ‘NoneType’ object has no attribute ‘items’: Can’t upgrade Plone 3 to 4.x

You may have seen an error like the one below when you’ve gone to upgrade your Plone site to something in the Plone 4.x series from Plone 3:

2011-09-14 08:43:32 ERROR plone.app.upgrade Upgrade aborted. Error:
Traceback (most recent call last):
  File "/home/david/.buildout/eggs/Products.CMFPlone-4.1-py2.6.egg/Products/CMFPlone/MigrationTool.py", line 175, in upgrade
    step['step'].doStep(setup)
  File "/home/david/.buildout/eggs/Products.GenericSetup-1.6.3-py2.6.egg/Products/GenericSetup/upgrade.py", line 142, in doStep
    self.handler(tool)
  File "/home/david/.buildout/eggs/plone.app.upgrade-1.1-py2.6 …

in Plone · Wed 14 September 2011

Plone 4: Local Zeo blobs conflict with Plone instance

As the title suggests, there’s a conflict between a Zeo database instance being run together with a Plone 4/Zope instance, and them trying to share the same blob storage folder.  But, this only happens if you misunderstand or incorrectly set the option of  shared-blob = off, and blob-storage to be the same location as for Zeo in your buildout. If that previous set of (seemingly jumbled) thoughts doesn’t make any sense to you, then move along, nothing to see here.

By default, at the time of writing, blob support within Zeo runs with the bushylayout, and creates …

in Plone · Tue 06 July 2010

David tries Plone 4.0a2 (Part 1)

Plone 4 is approaching!  Excellent!  Lots of new features to play around with and plenty more things to have to fix with the upgrade.  I’ve been keeping tabs on the change log of updates and it’s looking really good. Lots of little, but significant, changes are afoot.  Now, how about actually installing the Alpha 2 version of Plone 4 to see it for real? Let’s do it!

My steps are not going to work on your computer.  I don’t think you’ll be able to follow my words/commands exactly, but here goes anyway about my …

in Plone · Tue 08 December 2009