Missing or bad product in Plone
The error looks something like this:
TypeError: ('Could not adapt', <CacheTool at /bcf/portal_cache_settings used for /bcf/bbwebsite_wide_view>, <InterfaceClass Products.Archetypes.interfaces._schema.ISchema>)
The Zope cluster comes up but almost nothing within a Plone site is accessible - nothing from the site view and nothing beyond the container in the ZMI.
When we saw this, it was a missing product that was referred to within a product in use in the production environment, but which had not itself made it into the production environment. Once the new product was put into the right place, and the server restarted, all was well.
We started the cluster in foreground mode to find out what product was missing. See this article.