I wanted to play with my friend and we tried to connect to each other’s world(or servers) but can’t for some reason after we have updated the game these issues started to occur

Me and my friend was playing like normally then there was an new update to minecraft (1.2.6) and so we updated like everyone is.After we have done updating we proceeded to play again but we couldn’t we have tried everything we could but failed I decided to make a report about this