MOD won't work Season5

won’t allow mods with Population changes… Stuck at 200 Pop on custom and Skirmish

I had to completely redo my population mod for it to work in the new update, either do the mod yourself or wait for modders to upload an updated version.

What you are describing relates to game crashes as the update changes stuff in mods for whatever reason, but OP might also have another problem which is the inability of players joining the custom lobby to download the mod, then the host can’t start the game. There is a turnaround that can help but is impractical and players are usual impatient to do so. If you convince the players to download the mod/tuning pack before joining the lobby then you can start the custom game (the button won’t be greyed) with no problem. However this might require them to restart the game because visiting All Mods page only work after a fresh start and if you do something else you can no longer visit it until you restart.

Obviously for skirmish the second problem is irrelevant and all he has to do is to use an updated mod.