I'm getting a ton of errors in my transaction log, they are either invalid validation, invalid user, no txn_id, no action to take. How do I fix these as people actually have paid for these upgrades.
Not all of those are errors -- no action to take, for example, is just informative (as PayPal sends some requests along which we don't use).
However, invalid validation and invalid user are errors that shouldn't happen. Have you installed any add-ons relating to user upgrades? Have you imported from another software? Are you submitting payments through anywhere else on that PayPal account?