Paper Mario: The Origami King has been out in the wild for a bit: enough time for folks to spot some progress-hindering bugs.
While a few of them are hard to trigger they do in fact exist; and can gate your progress on the critical path or toward a 100% completion rating, which will unlock a secret ending. As of patch 1.0.1, which was released this week, a few of those have been squashed.
The "main" one that's been making the rounds involves a location where, if certain conditions were met, you wouldn't be able to re-enter the area. As of patch 1.0.1, you can "proceed normally" even if you've already encountered the bug. Another popular callout involved the game's inability to register a special enemy as "defeated" in your log book if a party member (AI) finished it off. That's also been fixed.
Finally, some broken hidden Toad locations have been fixed, amid a few rarer progression-halting bugs. I'm keeping things fairly vague, because the patch notes below outright spoil a few minor secrets and locations.
Version 1.0.1 [Nintendo]