The update patches a security issue, and Apple said everyone should download it.

Apple released its first iPhone Rapid Security Response update, called iOS 16.4.1 (a), on May 1. The company said the update is recommended for all users and it applies important security fixes to iPhones, but Apple didn't release security notes associated with the update.

To download the update, go to Settings > General > Software Update, tap Install Now and follow the onscreen prompts.

Some users saw an error message when installing iOS 16.4.1 (a) on their devices. The message read, "Unable to Verify Security Response," and it said they were no longer connected to the internet. If you see this error message, you can immediately retry downloading the update or try again later.

Rapid Security Response updates are a new type of device update Apple introduced alongside iOS 16.2 in December. According to Apple, Rapid Security Response updates provide users with important security fixes more frequently. These updates can help you mitigate iPhone security issues in real time, rather than make you wait for the release of a larger iOS update. Rapid Security Response updates are designated with a letter to differentiate them from other updates.

Apple didn't immediately respond to CNET's request for comment.

For more iOS news, check out what features could be coming to your iPhone with iOS 16.5 and what was included in iOS 16.4.1 and iOS 16.4.