Max Glenister

I’ve had a OnePlus 7 Pro sitting in a drawer for a couple of years. I used it from 2019, found it too big, got a Pixel 5a, and now I’m on the Pixel 7a. The usual thing, fiddling with an old gadget that’s been kicking about doing nothing. It’s a nice phone with nice features. Shame it’s stuck on such an old version of Android. Time to get LineageOS on there.

The bootloader problem

With the Android 12-based OxygenOS the bootloader can’t be unlocked. To get around this I needed to downgrade to Android 11 first.

The URLs floating around the internet for the official rollback packages are broken, the oxygenos.oneplus.net domain doesn’t serve them anymore. The files still exist on AWS though. Just swap the domain:

https://oxygenos.oneplus.net/OnePlus7ProOxygen_21.E.41_OTA_0410_all_2112101752_downgrade_3821c2d4496c48fc.zip

becomes:

https://s3.amazonaws.com/oxygenos.oneplus.net/OnePlus7ProOxygen_21.E.41_OTA_0410_all_2112101752_downgrade_3821c2d4496c48fc.zip

I found this via a thread on the OnePlus community forums.

Downgrading to Android 11

1. Download the rollback update package using the S3 URL above
2. Enable Developer Options (tap the build number 7 times in Settings → About Phone)
3. Enable USB Debugging in Developer Options
4. Push the file to the phone:

adb push OnePlus7ProOxygen_21.E.41_OTA_0410_all_2112101752_downgrade_3821c2d4496c48fc.zip /sdcard/

1. On the phone, go to Settings → System → About Device → System Updates → Local Install
2. Pick the zip, extract, and hit Install Now (the phone will reboot)

Unlocking the bootloader

After the downgrade completes:

1. Enable Developer Options again
2. Enable USB Debugging again
3. Reboot into fastboot:

adb reboot bootloader

1. Unlock the bootloader:

fastboot oem unlock

Installing LineageOS

The LineageOS installation guide for the OnePlus 7 Pro (guacamole) covers this in detail. The rough process:

Flash the partition images:

fastboot flash dtbo dtbo.img
fastboot flash vbmeta vbmeta.img

Reboot back into fastboot and flash the boot image:

fastboot reboot bootloader
fastboot flash boot boot.img

Factory reset from the recovery, then sideload LineageOS and GApps (I wanted the Play Store):

adb sideload lineage-23.0-20260202-nightly-guacamole-signed.zip
adb sideload MindTheGapps-16.0.0-arm64-20250812_214353.zip

Reboot the device and it’s done.

LineageOS 23 runs fine. An evening spent downgrading from Android 12 to 11 so I could upgrade to 16, as one does. Back in the drawer it goes.