What a Custom ROM Gives You, and What Stops Working

If you're flashing a custom ROM to extend your unsupported phone's life, you'll often have to unlock the bootloader - triggering a full data wipe and erasing your warranty. Beyond that, critical apps such as banking, payment, and some stock-feature processes commonly break when facing Google's SafetyNet or similar security checks.

The Price of Unlocking

Before attempting to unlock the bootloader on an unsupported device, users are commonly advised to back up all their data. That heads-up comes because you may not be able to recover some things. On many systems, the bootloader unlock itself triggers a full system wipe, starting you from a clean slate without user data. And if you change your mind, relocking the bootloader to solve the problem won't necessarily put your device in a trusted state or restore manufacturer guarantees.

What Usually Stops Working

Banking and payment apps are the categories most likely to trouble report or outright refuse to run on a device with a custom ROM. That's usually because apps such as banking and Google Pay will often show their own message, triggered by the failed results of Google's SafetyNet/Play Integrity checks that look for device integrity and state. The same failure risk seems to extend to some vendor and service apps indispensable to the phone's daily use, but sources vary on exactly which ones.

What Gets Worse, Not Just Different

When you flash a ROM that's not the original firmware, you're clearly enabling the restoration of app and service functionality controlled by code you don't receive from the manufacturer, but the change of source can alter what you're getting within the product. Many ROMs are based on generic open-source software such as AOSP rather than the proprietary stock firmware, which, depending on the device, can downgrade the camera image or video processing.

These losses commonly occur on self-shot content created or enhanced with device software. Custom ROMs frequently give an opportunity to enhance privacy and control, such as removing bloatware or imposing tight control over which developer apps can run in the background. But on some device hardware, the trade-off of losing image quality or raw photo-look freshness from the original firmware have been considered a real price of switching.

What Can Be Recovered

In some situations, however, users have reported some restoration of function lost after flashing to a custom ROM. Many users have seen fix successes when a custom ROM gains fixes from the community or developer to restore failed device integrity checks passed back to apps by Google's services. Magisk and other custom ROM systems sometimes include a system to give a modified SafetyNet setup to pass Google's integrity checks, but many observations note that the fixes don't always succeed or work every time.

Why People Still Do It

Regardless, there's a reason many daring users flock to potentially breaking their own phones with custom ROMs. The top gains cited include extending the working lifespan and performance of an older device. By keeping a no-longer-supported phone running for longer, from an upgrade or end-of-life update, a custom ROM is enabling the original hardware investment to go on for longer. When done skillfully, and accepted for the tech risks involved, the popular choice can give the user the chance for an experience and level of control which they aren't seeing in the stock firmware.

The Return Path

For some owners, the custom ROM solution succeeds and the phone is kept in use. But many end with a return. Does that mean you have to start all over? For this also, there are some real returns to the hard work. On most systems, reports indicate that if you wish to revert, you typically will need to restore the original parts from the stock firmware and do a full reinstall. Some user forums share reports that on some systems, that wipe that bootloader unlock did doesn't necessarily erase user data such as photos that isn't directly accessed through Android data partitions or backed up regularly.