I tested this using the proposed version of ubuntu-release-upgrader from Xenial and when I had dpkg version 1.17.5ubuntu5.5 installed I was not allowed to start the upgrade process. Once I installed the proper version of dpkg the upgrade to Xenial was allowed to proceed.
I tested this using the proposed version of ubuntu- release- upgrader from Xenial and when I had dpkg version 1.17.5ubuntu5.5 installed I was not allowed to start the upgrade process. Once I installed the proper version of dpkg the upgrade to Xenial was allowed to proceed.