Upgrade steps

The profile version of collective.polls 3 is 3000. One upgrade goes there from any 2.x version, and it is safe to run more than once. It never drops vote data.

Step	What it does
Re-apply the browser layer, type, workflow and permissions	Imports the browserlayer, typeinfo, workflow, and rolemap steps. Without the browser layer, the REST services do not exist.
Move votes to the 3.0 storage	Copies each poll's 2.x vote counts and voters to the new storage, and gives options stable ids.
Remove vote portlets	Deletes every 2.x voting portlet assignment.
Let anonymous visitors vote in open polls again	Grants the vote to Anonymous on every open poll that allows anonymous votes and whose folder anonymous visitors can see. Reinstalling 2.x could have dropped that grant.
Remove registrations of 2.x tiles and resources	Removes the collective.cover tile and the JavaScript and CSS resources from the registry.
Check that plone.volto is installed	Logs a warning when it is not, because polls cannot be shown without Volto. It does not install it.

See Upgrade from 2.x to run it.