If Android 11 becomes unstable, revert using (not fastboot). Download the correct ops file for your model. MSM bypasses all partition locks by rewriting at the Qualcomm Sahara protocol level.
Note: Download these files directly using your phone's browser, or download them to your PC and transfer them over via USB. Step 3: Prepare the File Structure
If you are facing persistent bugs, declining battery life, or simply miss the classic OxygenOS aesthetic, this guide will walk you through why and how to safely return your device to its original software. Why Downgrade? The Case for OxygenOS 11 downgrade oneplus 9 to android 11 exclusive
Before you begin, make sure you have the following:
: Since modern OxygenOS versions (Android 12+) often hide the "Local Upgrade" option, you may need to install the OnePlus Local Update APK to enable it. File Renaming : If your downloaded files end in , you must rename them to end strictly in (for firmware) or (for the update tool) for the system to recognize them. Step-by-Step Downgrade Process Prepare the Package : Copy the downloaded Android 11 rollback file to the root directory of your phone's internal storage (not inside any folder). Install the Update Tool : Install the Local Update APK If Android 11 becomes unstable, revert using (not fastboot)
Download and install the official (often called the System Update Tool). Open the newly installed System Update app . Tap the Gear Icon in the top right corner. Select the rollback .zip file from your root directory.
The installation process takes roughly 10 to 15 minutes. Once finished, tap . Your OnePlus 9 will boot into the classic OxygenOS 11 setup screen. Note: Download these files directly using your phone's
: Since modern OxygenOS versions hide the local upgrade option, you must install the OPLocalUpdate APK to perform the installation. 2. Prepare the Files
Go to Settings > System > Developer Options and turn off .