My unofficial thought is that it is a versioning error. Since you are now having a date/time error and I have seen other posts where updating to 4.1.2 fixed a time zone issue that someone was having (this post)
Hard for me to judge the production environment - my preference in this instance would be to finish the upgrade sequence and work on issues once complete - you could go down a rabbit-hole that isn’t worth it if finishing the upgrade could fix it… and the alternative of rolling back production when a third of the way through may be just as, if not more, painful.