Hey I'm trying to customize the registration process but seem to keep getting an internal error with console logs displaying Cookie “gc” has been rejected because it is already expired. Account.Register.Service.ss Cookie “NLPromocode” has been rejected because it is already expired. I've tried deleting all cookies but this seems to have no effect. Testing the registration in other browsers seems to not work either.

I don't know the answer but it sounds like you're still using Standard/Advanced Promotions and not SuitePromotions? And this sounds like an unexpected conflict?

I've removed the extension and it now goes through the registration process but still console logs the warning of the cookies so I'm not sure if they are causing the issue i'm having with the extension.

Well I would look at it the other way: your extension isn't causing the error messages. So that's good. What's causing the specific errors, I don't know. Are they actually blocking the user from completing actions, or are they just warnings?

Well i'd attempt to create a new registration where it should be valid but it would display internal error and not redirect but when i refreshed it would go to the checkout page.

Well, if you're using unedited source code and it's causing this problem, it sounds like a bug and perhaps you should talk to support about it

I had problems earlier deploy a theme i've now reverted back to the unedited base theme and i think its resolved my issue

Is it also possible that you are trying to apply an out of date promotion to an order? It's odd that it would cause this kind of problem but I don't know if it might

I think it was something completely unrelated I was passing in a custom field that when i tried to reimplement caused the same issue