[OnePlus 3T Guides, News, & Discussion] Chaplan:
Reverting to N the easy way...

I have already shared how to go back to N without the revert zips on this thread.

I have never used the revert zips and have been back and forth OB O and stable N/OB N with custom ROMs both N and O in between.

Getting back to any previous N setup with your /data included is possible and easy.

Unlocked Bootloader and TWRP are mandatory.

I go with the latest blu_spark TWRP.

It's Oreo based and works for N zips also, although I have done it on blu_spark TWRP N based and it worked as well. Wild.

A Data partition backup made on TWRP before jumping to Oreo OB is of course needed.

That should be backed up along with your internal storage elsewhere just for the sake of sanity, mainly if one has a cat as a pet (I don't but i backup it all up periodically nonetheless).

Flashing Oreo OB is pretty straight forward and all the needed info is already on the OP.

I will only focus on getting back to N as it was, before I made the jump to O, since a lot of misconceptions have been made/shared/stated/debated already and I haven't yet found a post that says it all!

Reverting to N:

1-On TWRP Wipe Data, System, Dalvik/ART cache and cache partitions. (Don't wipe internal storage).

Reboot to TWRP.

If you were on OOS N stable/OB :

2-Flash the OOS N build your were on, restore Data backup, flash root solution if needed, flash custom kernel if your are into it and reboot to system.

If you were on a custom ROM:

Step 1 is of course mandatory.

2- Flash OOS build that ships the FW you need for the custom ROM you are gonna use or download the correct FW+Modem and flash that instead. If the custom ROM works fine with OB FW just skip this step (what?), you will be flashing it afterwards so it's redundant.

3- Flash custom ROM, Flash Gapps, restore your Data backup, flash root solution if needed, flash custom kernel if your are into it and reboot to system.

Your internal storage is intact and you are back to your previous setup with all your apps and account logins, all is exactly as before the jump to Oreo, easy peasy.

I usually delete some stuff from internal when changing between ROMS, it's not mandatory but saves some space. Android folder (I like to let it be recreated now and then), OEM log folder (wonder why we still have this even on stable OOS builds) and a few more that pile up and are highly unneeded for the long run. I do this directly in TWRP but it can be done after boot with a file explorer or via MTP.

Disclaimer:

First, i have already said it, but i want it to be as crystal clear as it gets, I don't have a cat.

Second, I don't tell people to follow this path, users should do things the way it's more comfortable for them after they gather all the info they can on any given subject.

Third, this tutorial doesn't cover DM verity screen showing up and/or loosing TWRP but rooting and/or flashing a custom kernel will keep both away. There are other solutions also. Rule of thumbs, never boot to a clean stock boot.img (kernel) if you have TWRP. If you did follow the steps in the OP to get rid of DM verity nag screen and reflash TWRP via fastboot (it did cover it after all, i might edit this bit later to get rid of the nonsense).

Forth, i run encrypted storage at all times.

I'm just sharing my experience in such a matter because it works for me and should work for everyone if no deviations are made to the steps shared here.

Don't like it? Look the other way and don't do it.

If you go ahead and do this, follow every step and enjoy. :good: