For the installer for Ubuntu Touch to work successfully, it is essential that the version of the original operating system for which the port was created is installed. This depends on the device, but should be specified on the device's page. This is usually not the latest version available! For the Oneplus5(T), for example, this is version OxygenOS 10.0.1, and for the OP8T it is 11.0.13.13.
Note: There might not be an image available for the exact version you need. Then pick the one below that comes closest. Install that and then update via system updates to the required version.
If you are lucky, you can use the downgrade wizard integrated in OOS. To do this, download the appropriate file and proceed as follows:
Settings
About device
Info box with version information -> three dots menu
Local installation
Select file
Let's be realistic. Life rarely does us this favour.
Here is the second method using MSMDownloadTool.
Requirements:
PC with Windows 10/11 and administrator permissions
adb and fastboot installed (e.g. in the terminal via `winget install Google.PlatformTools)
Required image for OxygenOS (zip) including MSMDownloadTool v4 downloaded
OP8T, others?: info about the RAM type DDR4 or DDR5 (usually DDR4), shown e.g. with the app Device Info HW
Note: There is a pure Linux way to flash an image with so-called flash-all.sh scripts. However, I have not tried this and it is only intended for experienced users who know which file needs to be flashed to which partition. This is the, um, simple version...
The OSS image (zip file) usually contains the MSMDownloadTool in the correct version to install the right OS version. With this proceed as follows:
plug in your device
head for windows system updates and check optional updates, there should be a qualcom driver update, might need a search
open a terminal, check your device is recognized with adb devices, then enter EDL mode either with adb reboot edl or manually:
power-off your device completely
unplug the device from the computer
press & hold both Volume down + Volume Up, keep holding them
connect the device to your computer
now start the MSMDownloadtool as admin
your device should be recognised and marked as connected
select your version (EU, Global, India)
select the ram type (DDR4 or DDR5)
press start
now download and installation should start
once the process has finished, the phone automatically reboots (the entry becomes green earlier, wait for reboot)
after the reboot go to system updates and make sure to upgrade to required version of OxygenOS
Now proceed as usual:
enable developer tools, enable oem unlocking (may need wifi or mobile data to be on)
boot the device into fastboot mode via adb reboot fastboot or manually:
unplug device
shut down device
a) press & hold Volume Up, Volume Down, and Power keys together
b) press and hold Volume Down and Power, after vibration let power key go, in the boot menu select language, select advanced, select boot to fastboot
when in fastboot mode (NOT fastbootd!), plug the device in your machine, run fastboot devices to check that your device is recognized and ready to go, then run fastboot flashing unlock
on screen select "unlock bootloader" and confirm with power button
Note: There is also fastboot oem unlock. According to web sources, that may do exactly the same, but may also behave different depending on the manufacturer.
wipe data partition to format it as ext4 to remove android encryption either via boot menu (boot into boot menu, select advanced, reboot recovery), advanced, wipe or by booting into fastbootd mode (aka bootloader ) and running fastboot format:ext4 userdata
run the installer
Fingers crossed you now get a nice Oneplus device with Ubuntu Touch installed.
