Downgrade Oneplus 9 To Android 11 New! May 2026

Downgrading OnePlus 9 to Android 11: A Review of the Process and Implications

Downgrading a smartphone from a newer version of Android to an older one is not a common practice, but it can be necessary for various reasons, such as compatibility issues with certain apps or a preference for an older user interface. In this review, we'll explore the process of downgrading a OnePlus 9 from Android 12 (or later) to Android 11, the implications of doing so, and what you can expect. Downgrade Oneplus 9 To Android 11

Method 2: Fastboot Flash (If Local Upgrade Fails)

Required: Unlocked bootloader. Download the fastboot ROM of OOS 11 (not the OTA zip). Downgrading OnePlus 9 to Android 11: A Review

# Reboot to bootloader
adb reboot bootloader
IMS Service Keeps Stopping (Cellular Issues)
Fix: Go to Settings > Apps > App Management > Show System Apps > Search for "IMS" > Clear Data & Cache. Restart. Phone boot loops after downgrade

Phone boot loops after downgrade

Fix: Boot into Recovery (Power + Volume Down) → Wipe cache partition → Reboot. If that fails, wipe data/factory reset from recovery.

Step 6: First Boot (Patience Required)
The first boot into Android 11 can take 5-10 minutes. Do not force restart. The phone will eventually show the Android 11 setup wizard.