Android 11 — Downgrade Oneplus 9 To

Cause: You are trying to downgrade from Android 13 or OxygenOS 13.1 directly to Android 11. Fix: You must first downgrade to Android 12 (OxygenOS 12) using an intermediate rollback package, then downgrade to Android 11. OnePlus blocks direct major version downgrades.

This is the safest and recommended way to downgrade your OnePlus 9 to Android 11 without using a PC.

OnePlus officially provides "Rollback Builds" (downgrade packages) for users who want to revert from beta or stable Android 12/13/14 to Android 11. Downgrade Oneplus 9 To Android 11

Where to find them:

Example file name: Rollback_OxygenOS_11.2.10.10.LE15DA_210923.ozip Cause: You are trying to downgrade from Android

| Issue | Workaround | |-------|-------------| | "Verification failed" in Local Upgrade | Rename file to downgrade.zip, try again, or use MSM | | Fingerprint doesn't work after downgrade | Reboot twice, or re-flash persist.img from OOS 11 backup | | WiFi / Bluetooth broken | Flash OOS 11 persist + modem via fastboot | | Anti-rollback error (bootloop) | Your OOS 12/13 had higher ARB version – must use MSM Tool |

By [Your Name/Tech Writer]

The OnePlus 9 series launched to critical acclaim with OxygenOS 11 (based on Android 11) —fast, clean, and fluid. However, the subsequent updates to Android 12 (OxygenOS 12) and beyond introduced a controversial "unified" codebase with Oppo’s ColorOS. Many users report bugs, aggressive battery drain, altered UI logic, and removed features.

If you regret the update, you can go back. But be warned: Downgrading wipes all your data and carries risks. This guide will walk you through the official rollback package method. Example file name: Rollback_OxygenOS_11

⚠️ Important Warning:

Post your device model and current OOS version below for help.