Should have a single migration for 4.0.0 rather than multiple migrations. Anyone upgrading from 4.0.0.alpha to .beta should delete the following migrations from their project.

browsercms400.cms.rb
devise_create_users.cms.rb
kill_reset_password.cms.rb
create_cms_external_users.cms.rb

Then reinstall the browsercms400.cms.rb via rake cms:install:migrations. You will need to retimestamp the new migration so it won't run twice.