| Error Message | Solution | | :--- | :--- | | "Verification failed" | You are trying to downgrade from Android 13 directly to Android 11. You must first flash the (OxygenOS 12), then repeat for Android 11. | | "USB Device not recognized" in MSM | You need the Qualcomm 9008 drivers . Download them, then go to Device Manager > Right-click the unknown device > Update driver > Select "Qualcomm HS-USB QDLoader 9008." | | Bootloop after downgrade | Boot into recovery (Power + Volume Down) and perform a "Format Data" (type "yes"). The downgrade often corrupts user data partitions. | | Fingerprint sensor not working | Your persist partition is mismatched. Re-flash the Android 11 firmware via MSM tool again, but this time check "Reset fingerprint" in the tool options. |
Newer versions of OxygenOS often hide or remove the "Local Upgrade" option from the settings menu. You may need to install the to restore this functionality. downgrade oneplus 9 to android 11 exclusive