A bug in the HealthKit tool for developers of health and fitness apps prevented those apps from being released with iOS 8 last Wednesday. A week later, the fix is in--but the update also seems to be causing problems of its own for some iPhone 6 users.

Apple rolled out iOS 8.0.1 on Wednesday after promising on launch day that HealthKit apps would be "available by the end of the month." Wellness tracking is a huge priority for the company, with HealthKit allowing apps to pass information about your vitals back and forth. The forthcoming Apple Watch is also designed to track your health and fitness.

Other improvements included in Wednesday's software update:

Addresses an issue where third-party keyboards could become deselected when a user enters their passcode.

Fixes an issue that prevented some apps from accessing photos from the Photo Library.

Improves the reliability of the Reachability feature on iPhone 6 and iPhone 6 Plus.

Fixes an issue that could cause unexpected cellular data usage when receiving SMS/MMS messages.

Better support of Ask to Buy for Family Sharing for in-app purchases.

Fixes an issue where ringtones were sometimes not restored from iCloud backups.

Fixes a bug that prevented uploading photos and videos from Safari.

To install the update, go to Settings > General > Software Update.

Some Twitter users are reporting issues with cellular connectivity and Touch ID after installing the software update, so you may want to hold off--or let us know what you experience if you proceed with the upgrade.