Guild Wars 2

I’ve had a difficult time getting backpacks to accept crests or jewel addons. For the L80 spineguard you get from the storyline, it accepts anything fine. However, for the L60 guild packback, I’ve tried both L65 and L80 crests, as well as L80 masterwork and exotic jewels (the correct one that you can add).

The simplest answer I can think of is that only L80 backpacks can accept L80 addons, but can anyone clarify? Buying a separate L80 guild packback is rather expensive for a single test. Also I thought weapons and armors can accept higher runes/sigils so this would seem like a strange limitation.

Items like crests and jewels have a minimum level, which applies to the item they are added to, not just the player.

rule of upgrades, the level of the upgrade must at least match the level of the item

as your statement indicates that, you are using a 65 upgrade crest to a level 60 bag, so it is not possible