I currently offer two user upgrades ("Silver" and "Gold"). Users who are already "Silver", want to to be able to incrementally upgrade to "Gold" for the difference in price between the two (not unreasonable).
Since the User Upgrade system doesn't seem to have a way to do that directly, I...
I never saw an answer to this error - did anyone ever figure out the cause? I can login/logout as user just fine, but this error pops up every time I do so.