Just upgraded a few sites with 3.0.6 (from various previous versions, 3.0.1, 3.0.5 and 3.0.2 and followed all the docs) and every site is working perfectly following upgrades :-)
It also only took about two minutes per site as well.
Thank you for the quick fix to the unexpected critical issue, as always your hard work is very much appreciated.
Best wishes,
Paul.