Getting root access, flashing TWRP custom recovery and installing custom ROMs on OnePlus 3/OnePlus 3T are awesome, but it will trip the dm-verity (verified boot) check on the device. If tripped dm-verity check (a security feature), you will see the dm-verity warning on startup. If you are annoyed with this warning message, then there is a simple working solution to fix it – no need to flash anything on the phone.
If you are looking for a working solution to fix the dm-verity check error on your OnePlus 3T or OnePlus 3, then the below guide should help you. Though the workaround is for OnePlus 3T, it should also works with OnePlus 3, thanks to the XDA contributor th3g1z for the simple workaround. All you need to enter two lines of code via ADB.
Dm-verity (device-mapper-verity) is a security feature implemented on Android 4.4 and above in order to help prevent persistent rootkits (a kind of malware) that can hold onto root privileges and compromise devices. You can read more about the subject at here.
Note: The below guide assume that you have ADB and Fastboot driver installed on your computer.
Disclaimer: Follow the instruction at your own risk. We will not be liable if any damage occurs to your device and/or its components. It is recommended for technically talented users only
1. Enable USB Debugging on your OnePlus 3T in Developer Options.
2. Connect your device to your PC via supplied USB cable.
3. Go to the ADB or Platform tools folder and open a command window from there.
4. In the Command Prompt, enter the command: adb devices
[It should list your device, if not, install proper fastboot driver for OnePlus 3T on your computer]
5. Now, issue the below command to boot into fastboot mode:
adb reboot bootloader
6. Now, issue the below commands one-by-one:
fastboot oem disable_dm_verity
fastboot oem enable_dm_verity
Now, the annoying dm-verity check error message will not appear on boot up. If you have any query about this subject, leave it in the comment section below. (Source – th3g1z)