Users upgrading from Xenial to Yakkety may experience a crash running update-manager (after the upgrade) if it has been upgraded but python3-gi is not upgraded.
This was just a dependency change in update-manager so the python line numbers in the Traceback will not change. Subsequently, viewing the Errors bucket and confirming that the new version of update-manager does not appear in it will be sufficient.
The Ubuntu Error Tracker has been receiving reports about a problem regarding update-manager. This problem was most recently seen with package version 1:16.10.9, the problem page at https://errors.ubuntu.com/problem/78e1b63ebdb0df37a8e0ace381df3f7b2786a2e5 contains more details, including versions of packages affected, stacktrace or traceback, and individual crash reports.
If you do not have access to the Ubuntu Error Tracker you can request it at http://forms.canonical.com/reports/.