Hi quick question, I was reading Rogue Trader Core Rule Book and the section on upgrades says that it would tell me the limit of upgrades but I can't find it. Was this been fixed in an errata or another book? If not any advice would be welcomed thank you. I am specifically looking at what the limit in weapon upgrades and armor upgrades are.

The limit for Armour Upgrades is 3 (unless the GM says otherwhise). Check Hostile Acquisitions for rules for Armour Upgrades.

The Core doesn't put a limit to weapon upgrades (save for Sights, since a weapon may only have one), so it's up to the GM to use common sense on each particular case.