Read this thread.

Before starting ensure the device is charged to over 80%. It uses a lot of power setting up.

Download the rollback build OB25 (OnePlus6Oxygen_22_OTA_054_all_1908302047_fulldowngrade_f019784c78234a67.zip) from the link here

Enable developer options on the device by going into Settings, About Device and tapping build number till it tells you have Developer Options enabled.

Go to Settings, System and Developer Options. Enable USB Debugging.

Connect the device to the PC.

A prompt will appear on the device, so accept it.

Draw down the top of the screen of the device from the left side and you will see a Dialogue box with a cog that states something like Android Actions. Expand that and choose File Transfer.

On the PC copy the downloaded OB25 to the root of the device, i.e. do not put it in a folder.

Once coped over, disconnect the device and go to Settings and System Updates. In the cog at the top right of the screen choose Local Upgrade.

You should see the zip file you have transferred over. Tap on that and start the downgrade. It will ask to reboot at 100%, reboot and let it do it's thing.

Set up Android again, ensure you connect to Wifi and you are in Android 9. Enable Developer Options again and enable OEM Unlocking (this will be greyed out if you aren't connected to Wi-Fi).

Reboot to fastboot mode and Unlock the Bootloader - this involves having the ADB and Fastboot drivers installed on the PC and opening a terminal in the folder that contains them.

Run the command ./fastboot OEM unlock

Follow the instructions on the device, once the bootloader is unlocked, the device will reboot.

Set up Android again. Enable Developer Options again. Enable USB Debugging again.

Start up the Ubuntu Touch installer and connect your device too it. Accept the dialogue box on the device for USB debugging. Follow the instructions on the installer.

Before starting ensure the device is charged to over 80%. It uses a lot of power setting up.

Bugs on this device (the main ones) - battery drain, affects a lot of UT devices, it drains the battery quickly. If the battery is totally drained and you stick it on charge you will get a Qualcomm Crashdump notification. Leave it for about 20 minutes to 30 minutes then leaving it on charge, power up the device and it will reboot to Ubuntu Touch. When Powering off the device, Power off and leave the device for a few minutes. Then press the power button and Volume down button together until it reboots to the bootloader. Using the volume buttons, select power off - this will ensure the device is powered off. It doesn't quite power off properly so will run the battery down.

@MrT10001 thanks guys I knew something was not normal here. I hope someone figures this out as I think ubuntu touch on this device is amazing.

@ezst036 Wow, I found the OP6T one of the easiest phones to install! I'll put the next bit in bold to help others:

If the device is at the bootloader (fastboot mode) and connected and you start the installer, the installer will pick it up as example "sdm845". If you know which device you have manually select it from the drop down list in the installer and follow the on screen instructions.

The bootloader must be unlocked to install Ubuntu Touch and if the instructions indicate a specific version of Android must installed before, install that version, boot into it and set it up, enable developer mode and ADB/USB debugging before starting the installer. The reasons for the specific version of Android has to be installed is for things like Vendor BLOBS, specific bootloader, specific kernel.

To install UT on the OP6T I have always had to downgrade the Android version to Android 9 using this file

Fulldowngrade_wipe_18801_181024_2027_user_MP2_release.zip

This can be obtained from here. The link is still active at this date (11th February 2024).
Download it to the root of the device i.e. connect the device to the PC and set the USB connection to file transfer and copy the zip (STILL zipped) file to the device - NOT in a folder (i.e. the root of the device). Once done then go to Settings, System, System updates and with the cog symbol on the top right, choose Local Install and let it do it's thing. It will take about 15 minutes, reboot and leave you at the Android set up screen.

Set up Android again, and enable Developer options and ADB?USB debugging. Reboot to the bootloader.

Unlock the bootloader using fastboot oem unlock.

Reboot the device and set Android up again, enabling ADB/USB debugging.

Connect it to the PC and run the Installer.

The installer will then reboot the device and do most of the work for you. You will at one stage have to boot into recovery, the installer will do the rest.

@ezst036 You may have had issues due to the device being T-Mobile, but I have had many locked devices that I have installed UT to and it was only SIM locked, the UT install always went through.

If the device reboots and you get a message saying "Qualcomm Crash Dump", power off the device, charge the battery for a bit and boot it up again.

The stability of the device is not quite there yet, mainly due to the issue across devices with UT draining the battery. There is an app called BatterySaver for 20.04 by Lionel Duboeuf that will help.

I have no bricked devices due to installing UT (yet)!

@tomsome
Yes, the developer mode think is for Android users.
If you already have Ubuntu Touch, then this is already done as well as unlocking the bootloader (expect if you locked it back despite it being deprecated).

@ijiki30 Use this build to roll back:

OnePlus6Oxygen_22_OTA_054_all_1908302047_fulldowngrade_f019784c78234a67.zip

Download it from here.

There is a reason why Android 9 is used, something to do with Vendor BLOBs I believe (but don't quote me on that).

@ancientsounds I've had my problem solved following the instructions in this post

@christianBorg the 6t rebooting is a win, i think devs should replicate the process for rebooting mechanism, i use that to reboot tbh

@anon Sometimes leaving it for a few minutes resolves it. Glad it is resolved.

@danfro
Hello,
If the led notification discussion on OPT5
still interests you, would you like to find the continuation in
https://forums.ubports.com/topic/9592/notification-lights-not-working-topic-8775/4
Best regards

Is USB HDMI working?

@bable3 if you do a hard reset (power off) it should go past the crash dump on starting it up again. Possible sign of a weak battery.

@arubislander Thank you. I was trying that several times, and getting rather anxious about it not rebooting, but then finally it did reboot and all is now well again.

But I shan't be trying to use the Wireless Display again very soon ...

@kugiigi YES! That fixes it. Very many thanks!

Now I will disturb those around me less, and save battery

@hunter616 For both Focal (Pixel 3a XL) and Xenial (BQ E4.5) it recognizes the pendrives. Recognizing meens the envelope on the topbar lights up green, and I hear a sound. In Focal I can not eject the drives, so when I remove it from the phone and put another pendrive in, it does not react to the new drive anymore. In Xenial I don't see this behavior. After a reboot it works again.
Ejecting in Focal does work in the Terminal app ($ umount /media/phablet/name-off-pendrive)

Can you try after a reboot?

So you do not get the message the drive was attached. But have you also checked the filebrowser app if it shows up there? In the filebrowser you should tab on the hamburger menu.

Can you try the filebrowser app?

The drives are formated as isofs (Ubuntu install drive), msdos (Windows install drive 😲 )

The device needs the stock version of Android for UT to install and it has to be the version stated in the installer page which is the last version of OxygenOS 9.

Here is the useful resource page.

@FK_nero You need this ROM:

Fulldowngrade_wipe_18801_181024_2027_user_MP2_release.zip

Download from here.

Information here.

Hi @Hugehead ,

See: https://gitlab.com/ubports/porting/community-ports/android9/oneplus-6/oneplus-enchilada-fajita/-/issues/12

Thank you!

@MrT10001 ahh that would make sense. For now I can do that.