I’m one of the first kids on the block to be playing with Movable Type 4.2, I’d bet. My upgrade went smoothly until I tried to publish a new post, when I got a nice error about using a MTArchiveNext tag without a date context. Saywhat? My templates worked a moment ago.
Long story short (and written mostly for Google): MT 4.2 automatically added a handful of “archive mappings” to the Entry Listing template. Those archive mappings include ones (like category archives—which I’ve never used) that do not provide a date context, causing my date-based tags to fail.
Aaaaanyway, let me know if anything else broke. Maybe next time I’ll think twice before trying to upgrade something at midnight…