Can I upgrade aircraft while on an aircraft carrier?

I think I have before though I'm not sure, so I wouldn't put my money on it but yes

no, unless you bug it, but it's not worth since they will drop off the carrier this way

This was a while back so I'm not sure if its outdated;

I tried upgrading my planes whilst the aircraft carrier was moving; it was extremely buggy and it showed the planes patrolling at the edge of their combat radius of in the middle of nowhere, then they turned into truck convoys (in the sea!). But not to fret, because once they finished upgrading, they magically came back to the carrier

By the way the carrier was moving, maybe it wouldn't have been so buggy if it was stationary ¯\_(ツ)_/¯

I’ve upgraded planes on carriers before. But if at all possible, I would move them to an air strip first. As others have pointed out, carriers are very buggy.