Are you sure you didn't disable "base" mod by mistake?

How do I verify that I did not do that?

I've never worked with Factorio mods before.

I tried to load an old game. The "Map version" in the Load game screen says "0.14.21-0". The game was likely created on an even older version of Factorio and then upgraded.

I expected the game to load but I got the following error instead:
Unknown entity light-smoke (Maybe you loaded alpha save ...