Question:
(Rule 20F2 and 24) Page 26, Rule 20F2 says ground units may air drop in any hex except prohibited, mountain, wooded-swamp, or forest. Page 35, Rule 24 says units and supplies may air drop in any land hexes. Which is correct?

Answer:
Rule 20F2 is correct; Rule 24’s “may air drop in any land hexes, including hexes occupied by enemy units” is intended to let you know that you can drop in enemy occupied hexes, but I see how you misinterpreted the rule the way you did. Perhaps the rule should remove the “any” or even add a rules back-reference: “may air drop in land hexes (per Rule 20F2), including hexes occupied by enemy units.”

Source:
Errata published at http://www.hmsgrd.com/Files/Europa/Second Front/Second Front.pdf