[OnePlus 6 Questions & Answers] v1-valux:
Hello there,

I have some sort of a problem (although my phone is still working.. yet)

I recently flashed my OnePlus 6 with LineageOS 19.1 (coming from OxygenOS 11.1.2.2).

I flashed "copy_partitions.zip" first and then the official LineageOS 19.1 ROM without GApps,

but because I wanted to use some features, which needed at least the presence of Google Services, I flashed the "LineageOS for microG" (19.1) ROM.

Which worked like a charm.. besides I was very unhappy because of the lack of customization regarding color-theming and the changes made to the QuickSettings of Android 12 in general..

So I thought I could clean flash LineageOS 18.1 / ("Lineage for microG") to get the old theming back..

So what I did was installing the official custom LineageOS recovery from 18.1 (because microG had none for 18.1),

hit "Factory Reset" and afterwards applied the Lineage 18.1 zip over adb.

A message "Update package is older than the current build, expected a build newer than timestamp [...] but package has timestamp [...] and downgrade not allowed" along with the Question to install anyway appeared right after sideloading it to the phone.

I decided to hit "Yes" because I don't needed to backup any data from the phone and wanted to wipe clean anyways... (which I thought I did with "Factory Reset)

So I installed and afterwards rebooted to recovery to flash Magisk aswell..

After rebooting to system then, the phone entered the fastboot loop.

No matter what I do, it still doesn't boot to system after installing 18.1 from LineageOS recovery (also tried with the newest microG recovery from 19.1).

I also known you would wipe system, cache and data (and maybe vendor aswell) prior to a clean custom ROM flash (via TWRP)..

So flashed TWRP 3.6.2 (latest) for enchilada and tried to wipe my system, vendor and cache, but didn't manage to find "system" or "cache" on the advanced wipe menu, so I formatted and wiped data and wiped vendor.

Then installed LOS 18.1 via TWRP also..

But same problem - fastboot only.

also after my TWRP journey, sometimes when flashing the LOS recovery and booting it, a message appears on screen:

Failed to bind mount /mnt/staging/emulated/media/0 [...]

The thing is, I can install LOS 19.1 (microG) without any problems and it would boot,

but I just want to downgrade and I found no guide for my device (or any with ramdisk and A/B slots)..

And there is also no link to MSMDownloadTools for Android 10 (because onepluscommunityserver.com is offline)..

The links from this post and some other posts I found aren't working anymore..

- Is there a way to go back to LineageOS 18.1? What would be the intended way (not doing a downgrade but flashing clean)?

- Is my phone softbricked somehow? (partitions broken or corrupt?)

- Is it a firmware problem?

(I am on security patch from November 2021)

But I don't know what exactly happened to my firmware when flashing Lineage 19.1 over OOS 11.1.2.2

This is my first post as it is my first Android phone/flashing experience in general.. so I hope I got everything right from all I found out until now..

I really appreciate any help / even if it is just saying I messed up and need to go EDL mode... (if it truly is the case)

Thanks in advance.

You people are great!

o/