A spokesperson told the publication:

"With iOS 10.2.1, Apple made improvements to reduce occurrences of unexpected shutdowns that a small number of users were experiencing with their iPhone. iOS 10.2.1 already has over 50% of active iOS devices upgraded and the diagnostic data we've received from upgraders shows that for this small percentage of users experiencing the issue, we're seeing a more than 80% reduction in iPhone 6s and over 70% reduction on iPhone 6 of devices unexpectedly shutting down."

Apple also told TechCrunch that it has given the older iPhones the ability to restart without needing to be plugged in. Before the fix came out, people had no choice but to plug in their phones whenever an unexpected shutdown happens. In addition, the tech titan will roll out another feature in the next few days. If the latest version of iOS deems your battery to be too old and worn down, you'll see a notice in settings telling you that "your battery needs service."

Apple didn't give an advice on what to do if version 10.2.1 doesn't fix the problem for you. But if you've been experiencing the same issue, try installing the platform update first before getting your battery replaced.