Once on Android 11, apply these to prevent forced updates:
Verdict: Worth it only if you absolutely hate Android 12/13’s ColorOS merger. For most, it’s a temporary band-aid with significant downsides.
For many OnePlus 9 and OnePlus 9 Pro users, the update to Android 12—and the subsequent shift to ColorOS in certain regions—was a polarizing moment. While updates usually promise new features, many users found themselves longing for the clean, lightweight experience of OxygenOS 11 based on Android 11. downgrade oneplus 9 to android 11 exclusive
Whether you are looking to escape UI bugs, regain battery stability, or simply prefer the old aesthetic, downgrading is a viable option. However, it is not a simple "back button" process. This write-up covers the why, the how, and the critical risks involved in downgrading your OnePlus 9.
With the release of Android 12 (ColorOS/OxygenOS merge), many OnePlus 9 users experienced degraded performance, camera processing changes, and thermal throttling. Unlike official downgrade methods (which only allow rollback to Android 12), reverting to Android 11 exclusively requires bypassing OnePlus’s anti-rollback (ARB) protections and manually flashing the original firmware partitions. Once on Android 11, apply these to prevent
Warning: This process wipes all user data, increments the anti-rollback counter on some partitions, and permanently prevents future OTA updates from installing automatically.
OnePlus introduced ARB in Android 11 updates. The aboot and xbl partitions contain a rollback index. Attempting to flash an older index without modification triggers: Once on Android 11
Solution: Exclusive downgrade requires flashing a modified persist partition and using fastbootd (not legacy fastboot) with --disable-verity --disable-verification.