The Journey of Flashing Android 9.0 on a OnePlus 3

Preface

Can you imagine a phone released in 2016, three years later now, going from Android 6.0 at the start all the way to Android 9.0? This kind of system update cycle is pretty conscientious, I'd say～ This time upgrading to Android 9.0, even though it's an official ROM package, there were still a few small pitfalls. It took an afternoon and evening of tinkering to finally get it installed. Maybe it's also because I haven't flashed in a long time and I've gotten quite rusty.

Screenshots first

Downloading the system image

First, download the image from the official channel: The official Android 9.0 is now on its second version. The download link is as follows: http://www.oneplusbbs.com/thread-4693480-1.html

But some people on the forum said the second version isn't as good as the first, so I downloaded the first version. I don't think it really matters; neither has any major issues in use. The download link for the first version is as follows: http://www.oneplusbbs.com/thread-4676870-1.html

Flashing preparations

Backing up your data is a must. Data is very likely to be lost during the upgrade, so make sure to back up your data. Then prepare the various flashing tools. There are two cases here:

Official recovery

The first is if your phone isn't unlocked and you're using the official recovery. Then you don't need to fuss—just copy the ROM package to the root of internal storage and you can upgrade. See the official tutorial for details.

Third-party recovery

The second is if your phone is unlocked and you've flashed a third-party recovery. At this point there are two options: according to the official tutorial, flash back the official recovery and then manually lock the phone; the other, which is the one I used, is to flash the Android 9.0 ROM package directly with the third-party recovery, though that takes a bit of tinkering. Next I'll record my tinkering process.

Starting the system install hassle

Because the recovery version I had installed before was too old (twrp 3.0.x), I ran into a lot of problems. I won't go into detail about those earlier failed attempts.

First, go to the TWRP official website and download a relatively new recovery image (img format). Official site: https://twrp.me/ The version I chose is: TWRP 3.2.3-0 Released Just select your device model and download according to the site's instructions.

Next you need adb tools and phone drivers. Since I use a Linux system, I don't need phone drivers—just the adb tools are enough (which is actually the platform-tools from the Android SDK). As a (fake) Android developer, messing with this is also a required skill (flee～ Windows folks can check out this post: http://www.oneplusbbs.com/thread-4676940-1.html

Then we're ready to start

Flashing the new recovery image

Connect the phone to the computer with a USB cable and enable USB debugging. First run adb devices to see if the phone can be recognized. Only if it's recognized can you proceed with the following steps. Enter the following commands:

# 进入fastboot模式
adb reboot bootloader
# 刷入新的recovery镜像
# TWRP_recovery.img可以替换成你下载的镜像名称
fastboot flash recovery TWRP_recovery.img
# 重启进入recovery模式
fastboot boot TWRP_recovery.img

After completing the above steps, the new recovery is flashed. It seems you need TWRP 3.2.0 or above to flash the Android 9.0 package (just a guess, not actually tested).

After entering TWRP, just select install the flash package and follow the prompts～ Anyway it has a Chinese interface, very simple～ After flashing is complete, the first time you enter the system it may prompt a decryption failure, in which case you'll have to wipe all data, which is why I said above you must back up your data!!!

Appendix

• Complete list of OnePlus engineering mode commands and codes
• OnePlus 3 official forum: OnePlus 3