: Moving to an older version of Android requires a factory reset. Use cloud services or a computer to save your photos, contacts, and documents.
Newer OxygenOS versions (Android 12/13/14) often hide the "Local Update" option. You must install a standalone Local Update APK to bypass this. 2. Prepare the Files
Move photos, contacts, and documents to a cloud service or a PC. Battery Charge: Ensure your phone is charged to at least 30-50%. Verify Model/Region: Downgrade Oneplus 9 To Android 11
You’ve successfully downgraded to Android 11. Now, ensure your phone works perfectly.
Tap on the rollback .zip file you moved to your root directory in Step 2. : Moving to an older version of Android
To ensure stability and eliminate any residual bugs, it is strongly recommended to perform a Factory Reset : Go to Settings . Select System > Reset options . Choose Erase all data (factory reset) . Frequently Asked Questions (FAQ)
On Android 12, the standard "Local Install" option is often hidden. You may need to download and install the official OnePlus Local Update APK Prepare the Rollback File: You must install a standalone Local Update APK
If you run into any specific error codes during installation, tell me your (found under About Phone, e.g., LE2115) and your current Android version , so I can provide the exact step-by-step fix. Share public link
Verify SHA256 after download.
Paste the file directly into the folder of your phone. Do not place it inside any existing folder. Step 4: Install the Downgrade Firmware
You must download the correct downgrade package for your region.