Error only when deployment target == 7.x

All my Xcode projects gave me errors only when deployment target is iOS 7.x and I don't understand why.

In particular I receive the following error when I click on a button:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Application tried to present a nil modal view controller on target

I don't have any problems with deployment target >= 8.x.

Any ideas?