After releasing three iOS 9.2.1 beta versions to developers, Apple has finally deployed the public version to its devices.

"This update contains security updates and bug fixes including a fix for an issue that could prevent the completion of app installation when using an MDM server," says the Apple update notification.

The new iOS 9.2.1 is a small (41.1MB) incremental update. The firmware comes with security updates (more details, HERE) and fixes the bug that used to prevent app installation procedure while using MDM (Mobile Device Management) server, the one used by corporate employees for working purposes.

However, we are not sure whether this update fixes the bug in the battery percentage meter in iPhone 6S and iPhone 6S Plus.

Just a few days ago, Apple acknowledged the glitch in battery meter and assured consumers that the company is working to fix it and release a software patch soon. Until then, the users can tweak the iPhone settings for temporary relief.

Read more: Apple iOS bug alert: iPhone 6S, 6S Plus battery percentage not updating [How to fix it]

In a related development, Apple has released iOS 9.3 beta to developers. It is said to come with Night Shift, multiple user account option and many other features.

Read more: Apple iOS 9.3 beta out; brings Night Shift mode, Security upgrades to Notes and more

How to install iOS 9.2.1 update on iPhones, iPads and iPod Touch:

Via OTA (Over-The-Air):

1. Settings >> General >> Software update

[Tip: Users who want to install the update directly on the device via OTA, make sure to clear enough device storage space and also make sure the device has more than 50% battery life, before downloading the new OS firmware]

 Via iTunes

1. Back up your iPhone or iPad with either iCloud or via iTunes.

2. Launch iTunes on your Mac or PC.

3. Make sure you're on the latest version of iTunes. Go to About and then Check for Updates or visit

4. Plug in your iPhone, iPad, or iPod touch if it isn't already.

5. Click on iPhone, iPad, or iPod in the top left navigation.

6. Click on the Check for Update button in the first section that contains information about your device and alternately you can click restore instead if you'd like to do a clean wipe with updated software.

7. An update should be recognised, click on Download and Update in the popup menu and agree to any terms or conditions.

8. Unlock your device with your passcode if prompted in order to continue with the upgrade.