Installed 16.04/dev to OP3T today with these steps

xet7

Hi,
I installed 16.04/dev to OP3T today (after having OxyxenOS and LineageOS for a little time, coming back to UBports).

After LineageOS, I installed OxygenOS back, with all checked first install and format. That did not have errors.
I clicked at Settings/info/OxygenOS some version number multiple times to enable developer mode.
From developer mode enabled USB debugging. Then rebooted to fastboot with volume up and power.
Unlocked:

sudo apt -y install adb

sudo su

fastboot devices

fastboot oem unlock

I used UBports Installer 0.10.0 AppImage (as normal user, chmod +x ubports...appimage , ./ubports...appimage) to start install of Ubuntu Touch 16.04/dev, with checkboxes enabled to first install and format.
At TWRP, when Advanced Format complained about volumes mounted, I rebooted back to recovery mode so had those formats done again successfully.
I had the timeout while installing Ubuntu Touch issue, so I used TWRP terminal to look at /etc/fstab and format to ext2 those data+system+cache like this, with that device name and number:

cat /etc/fstab

ls /dev/block/

umount /dev/block/<device>

mkfs.ext2 /dev/block/<device>

reboot

I used UBports Installer to install 16.04/dev without checking first install and format options.
Install success. Rebooted 2 times (first reboot did bring some error, 2nd boot booted to Ubuntu Touch, so reboot enough times).

arubislander

and format to ext2

Is ext2 the recommended filesystem? Why not ext4?

xet7

At TWRP terminal, using command to format to ext4 did not work, maybe TWRP terminal does not have ext4 formatting support. Using ext2 worked for me.

Sure if using ext4 instead important to you, you can try some other way to format those partitions.

MrT10001

@xet7 it should do. EXT4 is a common feature of TWRP. OnePlus devices usually have the data partition on EXT4 anyway.