This is a bit of a niche case but here goes:
I was in a fractal run a short while ago, and was dropped from the game. This occurred after the 3 hour patch window, which was announced while my party was in fractals. As I was dropped from guild wars 2, I then had to patch my game before logging in. After logging back into the game, I was unable to rejoin my party in fractals, presumably due to them being on a previous version of the game. This occurred during the Jade Sea fractal.