I don't know if this fits here but I get this error with my custom origin.

I'm trying to make a nymph origin upgrade into a Poseidon origin after killing an elder guardian. for this, I installed BlazeandCave's Advancements Pack. I'm using the_deep_end.json advancement. Maybe I quoted something wrong but for the life of me, I can't find the mistake. It says its missing "condition" and "origin", but I have them.
Please help.

Maybe I'm missing something else, but the wiki specifies the upgrades need to be an array of upgrades, not a single one, and the condition is an identifier, so try:

"upgrades": [
	{
		"condition": "blazeandcave:adventure/the_deep_end",
		"origin": "co:poseidon",
		"announcement": "Congratulations! Press [O] to see your newfound powers!"
	}
]