Even with careful planning, you may encounter problems. Here are some common issues and potential solutions:
Download the exact rollback package that matches your specific regional variant (NA, IN, or EU). Installing the wrong regional firmware can cause network connectivity issues. Step 1: Download the OnePlus 9 Android 11 Rollback Package Downgrade Oneplus 9 To Android 11
Download the firmware file. It will be a large package (usually between 3GB and 4.5GB) ending with a .zip extension. Even with careful planning, you may encounter problems
Downgrading your OnePlus 9 to Android 11 is a straightforward process using the official Local Update method. While it requires a full backup and a careful download, the result is a return to the fluid, battery-efficient, and camera-focused OxygenOS that made the OnePlus 9 a fan favorite. Step 1: Download the OnePlus 9 Android 11
Download the official (often called the System Update app stub) from a trusted forum like XDA Developers or OnePlus Community.
Move your downloaded Android 11 rollback .zip file to the root directory of your phone storage. Open the newly installed app. Tap the Gear Icon in the top right corner.