Live and Learn......  I noticed my MES future trades was frozen this morning.  Called Interactive Brokers.  Since I had the contract expiring today, they freeze the trades first thing in the morning and close all positions at that price.  They will release the margin in the next hour or so, so I can use that to buy the next contract in line, although the old contract won't disappear from my account until tomorrow.  One would normally assume you had to the end of the day on expiration day to roll forward.......  Maybe other brokers handle it differently.