OnePlus 9 / 9 Pro: Switch From ColorOS to OxygenOS Without Bootloader Unlock

Prerequisites

• To begin with, take a complete device backup. This is because the below process will wipe off all the data from your device.
• Moreover, this switch will be carried out via the Downgrade firmware. So make sure to download the correct Downgrade package from the below links. Likewise, we have also attached the original ColorOS file for your device, just in case if anyone needs it [Credits: XDA Senior Member mlgmxyysd].
  • Color OS for OnePlus 9
  • Oxygen OS for OnePlus 9
• Once you have downloaded the downgrade firmware, transfer it to your device’s Internal Storage.

That’s it, these were all the requirements. You may now proceed with the steps to switch from ColorOS to OxygenOS on OnePlus 9 and 9 Pro.

Switch From ColorOS to OxygenOS

1. Head over to the Settings page on your device.
2. Then go to System and scroll to the Software Updates section
3. Tap on the gear icon situated at the top right and choose the Select installation package option.
4. If you cannot access this option, then it’s because there are pending updates available. So consider either downloading and installing this update or cancel it altogether.
5. If you are planning to cancel it, then go to Settings > App management and select App list.
6. Then tap on the overflow icon situated at the top right and select Show System. This shall bring up a list of all the system apps.
   
7. Scroll to the Software Update app and go to its Storage usage section. Tap Clear Data > OK and then turn off your internet.
8. Anyways, once you have dealt with the pending update, the ‘Select installation package’ option should now be accessible.
9. So select the downgrade firmware that you had earlier downloaded and hit the Install Now button.
10. Wait for the process to complete. Once done, you will be notified to restart your device.
11. Do so and your device will now boot with the newly installed OS skin.

So these were the steps to switch from ColorOS to OxygenOS on OnePlus 9 and 9 Pro. If at any point in time you wish to revert to ColorOS, then here’s what needs to be done.

Switch from OxygenOS to ColorOS

1. As before, get hold of the appropriate downgrade firmware from the above Prerequisites section.
2. Then go to the Settings menu followed by System.
3. Select System Updates and tap on the gear icon situated at the top right.
   
4. Then choose the Local Upgrade option, navigate to the downloaded firmware and select it.
5. Finally, install the package and wait for the process to complete.
6. Once done, reboot your device and your task stands complete.

With this, we conclude the guide on how to switch from ColorOS to OxygenOS on the OnePlus 9 and 9 Pro devices. Furthermore, we have also listed out the instructions to make a switch from OxygenOS to ColorOS.

If you have any queries relating to any of the two methods, do let us know in the comments. Likewise, here are some iPhone Tips and Tricks, PC tips and tricks, and Android Tips and Tricks that you should check out as well.