Bonjour,
I'm at the beginning of a game, I have two iron mines (2x2 = 4 iron units) and the game pretends I cannot upgrade my warriors any more although I only upgraded one!
The iron counter on the top is ok (3 remaining iron units)
The warriors are in my territory.
I tried to reload but it did not help.
See snapshots and saved game below.

View attachment BugIron1.Civ5Save
Note: there's another problem with iron: if you're using all the iron units available, on upgrading the corresponding combat units I get wrong alarm messages pretending that I'm using too much iron!
I'm at the beginning of a game, I have two iron mines (2x2 = 4 iron units) and the game pretends I cannot upgrade my warriors any more although I only upgraded one!
The iron counter on the top is ok (3 remaining iron units)
The warriors are in my territory.
I tried to reload but it did not help.
See snapshots and saved game below.

View attachment BugIron1.Civ5Save
Note: there's another problem with iron: if you're using all the iron units available, on upgrading the corresponding combat units I get wrong alarm messages pretending that I'm using too much iron!