Haven't had a chance to double check this, BUT...

Was playing the Sengokku Shogunate Conquest, and I was unable to Upgrade my Daimyo. I have played before, and this hasn't been a problem. I suspect the reason may have been that I got access to iron VERY late, and so was trying to Upgrade from Shogun-1 to something like Shogun-8.

Yes, I had a Barracks. Even tried different cities with barracks. Even went to the city with a barracks AND iron in its direct radius. No luck.

This combined VERY late in the game with that other bug: Ninjas can attack cities, with game-ending shock and horror.

Sorry I haven't been more methodical about this. Just wondering if anyone else had experienced similar...?

Did you have the needed gold? Shogun1->Shogun-8 would take in the ballpark of 480 gold.

Did you have the needed resources too? A gamesave would also help.