OnePlus just made bootloader unlocking riskier than ever

OnePlus has reportedly started making a major behind-the-scenes change that could permanently affect bootloader unlocking, custom ROMs, and even basic software downgrades on its phones. The company had previously announced a new system that would limit bootloader unlocking, and it looks like it’s finally starting to implement it.

According to Droidwin (via XDA Member AdaUnlocked), OnePlus has quietly introduced Anti-Rollback Protection (ARB) with ColorOS 16.0.3.500/.501/.503 updates (based on Android 16) on select devices. This isn’t a normal software restriction, it’s a hardware-level fuse that gets permanently tripped the moment you install one of these builds.

As the publication explains, ARB works by blowing an e-fuse on the motherboard that updates the device’s security version. Once tripped, it cannot be reversed through software. The only way back would be to replace the motherboard.

ARB is part of Android’s Verified Boot framework. It was introduced to prevent downgrades to older, less secure firmware. Devices from the likes of Xiaomi, POCO, Redmi, Google, and others have used ARB for years. The protection also mirrors how Samsung Knox works. If you unlock the bootloader on Samsung phones, you end up tripping the fuse. However, unlike ARB-enabled phones, Samsung’s implementation isn’t so stringent. Samsung blocks the bootloader-unlocking process, but usually doesn’t hard-brick the phone if you try.

So with ARB on affected OnePlus phones, you won’t be able to downgrade to any firmware older than the ARB-enabled build. Flashing older custom ROMs will also likely cause an instant hard brick, and traditional unbricking tools won’t work since the damage would be at the hardware level.

Droidwin confirms ARB is already live on the following devices:

• OnePlus 13 and 13T: ColorOS 16.0.3.501
• OnePlus 15: ColorOS 16.0.3.503
• OnePlus Ace 5/Ace 5 Pro: ColorOS 16.0.3.500

The OPPO Find X8 series is considered at high risk, meaning ARB might also be live on phones in the lineup. Meanwhile, the OnePlus 11 and OnePlus 12 could be next in line to be impacted by the new system.

It’s important to note that right now, ARB has only reportedly appeared on ColorOS. But given OnePlus’ shared codebase, it could also arrive on OxygenOS in a future update.

OnePlus has also reportedly removed official downgrade packages for the OnePlus 13, meaning even previously sanctioned rollbacks could now brick devices.

For now, if you care about bootloader unlocking or custom ROMs, it’s best not to install any update ending in .500, .501, or .503.