toolbar missing from TinyMCE in Plone - html-editor

Question

When I want to add a Page in Plone the toolbar is missing from the TinyMCE wysiswyg editor's text area. Here is the error message I get:
Traceback (innermost last):
Module ZPublisher.Publish, line 126, in publish
Module ZPublisher.mapply, line 77, in mapply
Module ZPublisher.Publish, line 46, in call_object
Module Products.CMFPlone.FactoryTool, line 453, in __call__
Module ZPublisher.mapply, line 77, in mapply
Module ZPublisher.Publish, line 46, in call_object
Module Products.CMFFormController.FSControllerPageTemplate, line 91, in __call__
Module Products.CMFFormController.BaseControllerPageTemplate, line 28, in _call
Module Products.CMFFormController.ControllerBase, line 231, in getNext
Module Products.CMFFormController.Actions.TraverseTo, line 35, in __call__
ValueError: Unable to find update_version_before_edit
(The toolbar did show in the editor after I installed Plone for the first time. Another wysiwyg editor, Kupu, works fine).
As a newcomer to Plone I would very much appreciate any help in solving this problem.
Thank you for your assistance.

Answer 1

It seems you have upgraded the Plone version and there's some upgrade step missing. This can happen if your Plone Site is not upgraded to the file-system version.
Try to following steps in your actual Plone Site (please, backup first!):
Go to the ZMI of your Plone installation (site_url/manage)
Select the "portal_migration" tool
If you see a button called "Upgrade" click it, and try again adding a Page.
If you see "Your Plone instance is up to date" or the problem continues after the upgrade, then follow the next steps
Select the "portal_setup" tool
Select the "import" tab
In "Select Profile or Snapshot" select "CMFEditions"
Scroll down and click "Import all steps"
If your Plone installation is correctly installed and there's no version conflict, any new Plone site that you create inside the same Zope instance should be working fine. This steps can be useful to fix a Plone site created after the upgrade.