One of the biggest disadvantages of rooting is that it can be a monthly update with every new security patch. For other phones, you may have had to completely free up the device, perform inventory recovery, or possibly load all of the factory images onto Flash for a new update. Fortunately, OnePlus has made this process extremely easy for us modders.
It used to be a bit complicated in the older days of the rooting scene, but you can now easily upgrade to new devices like your OnePlus 6T while keeping root. It's almost as simple as native downloading and installing an OTA update on a standard device, but not completely . Let me show you the few quick steps you need to take to update your OnePlus 6T without worrying about the entire hopping.
Start the update of your OnePlus 6T. You must first download the latest update file from the official OnePlus website to your phone's internal memory. The file is quite large, so depending on the network connection, it can take up to ten minutes.
Step 2: Make Sure You Have Magisk  It is extremely important that you download the latest ZIP file from the Magisk Installer in your phone's internal memory so you can update after updating. If you skip the Magisk Flash before the next boot, you may end up in an endless boot loop after installing the OTA update. Magisk needs to be flashed to install a few patches after the update, so you can properly boot into Android again.
Just like Magisk, you should use the TWRP installer for retention on the internal Memory of your phone. This is because you can permanently save TWRP to Flash after applying the OTA update. Otherwise, inventory recovery will be reset to your system. If you forget to flash TWRP before rebooting, you must temporarily boot from Fastboot mode to TWRP to flash it again.
If you have the latest OTA update for OnePlus 6T installed and Magisk and TWRP installers installed on your internal storage, you must restart your phone in the TWRP recovery environment. If you have not already done so enable advanced reboot, and you can press and hold the power button to select the Restore option. Once you have done this, your phone should restart immediately and start to start the TWRP Main Menu.
Step 5: Install the OTA Update
On the TWRP Main Menu, tap Install and then Install. Locate the folder to which you downloaded the three files from the previous steps. First, tap the OTA update file to add it to the installation queue. You then want to enable the Swipe to confirm Flash slider to begin installing the OTA update.
The update includes the entire operating system and core files for the Oxygen operating system, so you can expect the installation time to be at least a few minutes. Sometimes it may seem frozen in the first step, but you have to be patient before continuing with the second step.
Once the first file is installed, press the backward arrow to return to the previous screen. Then tap on the installation file for TWRP and install it in the same way as before. Once this is done, repeat the same procedure for the Magisk installer.
Alternatively, you can add all three files to the download queue at once, if you want, but you may need to reload Magisk before the reboot becomes due to a strange error in the batch process. You need to make sure Magisk is flashing properly, or the phone probably will not boot until you run a Magisk flash again.
After all three files have been successfully installed, tap The "Reboot System" button. From here you should be good! When the boot process is complete, you should now get the latest Oxygen OS update for OnePlus 6T with full root access.
As a funny side note, the same installation process works for the OnePlus Beta builds as well. So you can test all the latest updates from the beta versions of Oxygen OS while maintaining root access. Once you've finished testing these updates, you can skim over the stable version again using the same instructions. Have fun!