No comments, no suggestions, so here's what I'm doing.
1. Restore from backup which returns me to the off season.
2. In pre-season I'll make sure that I generate a new schedule -- and I'll check all my minor leagues, though they didn't seem to have a problem before. (Not even those that expanded to support the major league expansion.)
I'm losing about 3 months out of my universe with this, and a few days of real time with my game, but hey, I'm retired so I have nothing but time.
And I've learned (again) a valuable lesson. Take nothing for granted unless you are willing to risk paying for some of your assumptions down the road.