Moderator, Omni, Omni/PR, Omni/Games, FlyerTalk Posting Legend
Join Date: Oct 2004
Location: Between DCA and IAD
Programs: UA 1K MM; Hilton Diamond
Posts: 72,475
Special meal requests will not block an upgrade.
You may find that after an upgrade, they do lose your special meal request (that has almost always been the case IME), and you are best served calling in at least 24 hours in advance to reconfirm. Inside 24 hours, you're out of luck as they can't put in a new special meal request.
If you had a special meal in Y and got upgraded inside 24 hours, you may be able to get them to serve it to you in J, as they likely already catered the special meal.