Any specific you encounter during the process.
Likely Cause : The downgrade process encountered a critical error. Solution : You will need to use the more comprehensive MSM Tool (Method 2) to properly restore your phone.
The local upgrade method using official OnePlus rollback packages is the easiest and safest way to downgrade your OnePlus 9 from Android 12 or newer to Android 11. downgrade oneplus 9 to android 11 exclusive
Run MsmDownloadTool V4.0.exe as Administrator. In the login prompt, choose user type: .
Ensure you have a stable Wi-Fi connection to download large files. Any specific you encounter during the process
Path A — Official local rollback (recommended if OnePlus provides an official rollback package for your build):
OnePlus provides official rollback packages packaged as .zip files. You must download the specific firmware that matches your phone's regional variant. OnePlus 9 OxygenOS 11 Rollback Package Europe (EU): OnePlus 9 OxygenOS 11 Rollback Package North America (NA): OnePlus 9 OxygenOS 11 Rollback Package The local upgrade method using official OnePlus rollback
By following these steps, you should be able to successfully downgrade your OnePlus 9 to Android 11. However, proceed with caution and at your own risk.
Likely Cause : You may have downloaded the wrong MSM package for your specific device model. Solution : Search for the exact MSM tool version that matches your OnePlus 9's model number and region.
