Can I upgrade my iPhone 3G beyond iOS 4.2.1?

The iPhone 3G officially supports up to iOS 4.2.1. It cannot be updated to iOS 5 or any later versions because the hardware lacks the necessary processing power and memory required for newer operating systems. If you are trying to install apps, you might occasionally be prompted to download an older, compatible version of an app if you have previously purchased it on your Apple ID using a newer device. Some users also look into custom firmware projects like Whited00r, which attempts to bring newer features to older hardware, though this does not provide true iOS 5 app compatibility. Ultimately, for access to modern applications, a newer iPhone model is required.