Without plone.app.upgrade, the plone-upgrade page does not work.

[mauritsvanrees]

What I did:

• Start a 6.1 site with only Products.CMFPlone.
• Use a database copy from Plone 5.2 (or 6.0).
• Go to @@plone-upgrade. It shows you need to upgrade the site.
• Click to upgrade and you see an error that the site did not reach the required version.

This is logical, because the page needs plone.app.upgrade: the upgrade steps are define there.

What I expect to happen:

See a message on the page, before you even try anything: "The plone.app.upgrade package is missing. You need it for running upgrades."

What actually happened:

I got an uninformative error, and no hints on the console.