First time this issue

[ChicaBuena]

I've been canning pickled red onion for years now but never have i ever had a problem with canning lids pop up. What can be the problem, and should i throw them away or they're safe to eat?

 

[jerick_s]

Unfortunately, if the lid popped up, the vacuum seal is broken, and it's not safe to eat.
When in doubt with home canning, I think it's really best to err on the side of caution!

 

[Abdul Muhamed]

Actually, if you canned them for the correct time and a few lids didn't seal, you can refrigerate them and they will be fine as long as you see the problem the same day. If you find popped lids on jars that have been sitting on a shelf, then NO you shouldn't risk eating them. The issue could be small chips in the mouth of the jars or faulty lids. I remove the rings and make sure each one has sealed before I put them on the shelf. Out of say 60 quarts of stuff, I may find 1 or 2 that "unsealed" on the shelf. No big deal as I generally can more than I need.

 

[ChicaBuena]

Actually, if you canned them for the correct time and a few lids didn't seal, you can refrigerate them and they will be fine as long as you see the problem the same day. If you find popped lids on jars that have been sitting on a shelf, then NO you shouldn't risk eating them. The issue could be small chips in the mouth of the jars or faulty lids. I remove the rings and make sure each one has sealed before I put them on the shelf. Out of say 60 quarts of stuff, I may find 1 or 2 that "unsealed" on the shelf. No big deal as I generally can more than I need.

That's what's bothering me. It were 3 in a batch of 15, which is way too much. I usually check the lids dna they seemed fine. Also, I noticed them after a few days and didn't want to risk it so I threw them out. I'll try to tripple check the lids and jars next time and hope I catch any problems before canning.