[OnePlus 3 Guides, News, & Discussion] EpicLPer:
Hello there!

Today, after a bit of tinkering around I managed to get my OnePlus 3 in a decrypted state without losing data!

However, this is

NOT

a method where your data will remain on the phone, it requires you to copy a backup to your PC and then copy everything back + fix permissions. In this guide you'll completely wipe/reset your phone prior to restoring everything.

FAQ:

Q: Why do I need an undecrypted phone?

A: So far (as of today, 06.07.2016) multiboot will not work on encrypted phones. That's probably the only reason why you'll ever want to decrypt your phone.

Q: Will updating the ROM force encryption again?

A: If you're using OxygenOS (or another encryption forcing ROM), yes. However if you flash the Full ROM ZIP and immediately after that SuperSU (DO NOT USE SYSTEMLESS OR IT WILL ENCRYPT AGAIN!!!) WITHOUT REBOOTING it'll not encrypt the device again. (Thanks to [MENTION=5377508]JumboMan[/MENTION])

Q: I've followed your guide but my phone got encrypted again!

A: You've probably used the Systemless SuperSU version which does indeed not prevent your device from being encrypted again. Use the normal version available HERE.

You'll need

:

A PC (obviously)

Unlocked OnePlus 3 (will probably work on other OnePlus phones, not tested!)

TWRP Recovery (follow THIS LINK for a guide)

About 50 GB of free space on your PC (depends on how much data you have on the phone)

ADB and Fastboot drivers installed on your PC (to get those connect your OP3 to your PC, as storage choose MTP, open the emulated OnePlus CD-Drive and install those drivers)

(Optional) 15 Seconds ADB Installer

A bit of time, roughly 30 minutes to 1 hour

!!!DISCLAIMER!!!

I'M NOT RESPONSIBLE FOR ANYTHING YOU'RE ABOUT TO DO HERE, THIS GUIDE IS PURELY WRITTEN "OUT OF MY HEAD" AND I CANNOT CONFIRM ANY OF THE FOLLOWING STEPS ANYMORE!!!!

ONLY DO THIS IF YOU KNOW HOW TO RECOVER FROM A HALF-INSTALLED OR COMPLETELY WIPED SYSTEM!!!​

How To:

READ AND ACKNOWLEDGE THE DISCLAIMER ABOVE!

Done? Are you really sure? ... Okay!

If you don't need your data backed up simply start at Step 10 and ignore the restore parts after that.

Still on OxygenOS (or any other ROM) make sure you've enabled ADB in Developer Options and connected + allowed your PC at least one time, else ADB in TWRP will not work.

If you have Titanium Backup, create a backup of all your apps before starting. Just in case, you never know...

Once done boot into TWRP (see above for an installation guide)

Create a normal TWRP backup

Type in "adb devices" to check if you're allowed to use ADB inside TWRP. If it says "unauthorized" refer to Step 1 again.

Once done open up a CMD on your PC and cd to the directory you want all your backup-files to be (or navigate via Windows Explorer to the folder, hold "Shift", right-click and choose "Open command window here...")

Type in "

adb pull /data/media

" and wait. Depending on the size this can take a few minutes.

After that's done make sure all your files are here and ADB is not reporting any skipped files.

Checked all your files? Okay!

In TWRP choose "Reboot" and "Bootloader". This will put your phone into Fatboot mode.

Type in "fastboot devices" to check if your phone is recognized. If not go into device manager, find the Google Bootloader drivers and install those.

NOW IS YOUR LAST CHANCE TO MAKE SURE EVERYTHING'S BACKED UP AND THERE!

Next type in "fastboot format userdata" and hit enter. This will completely wipe your device.

Boot back into TWRP by using the volume rocker and the Power Button.

ADB is probably not working now (will only report "unauthorized"), MTP however still works. Copy the TWRP folder we backed up earlier onto the device again.

Once copying finished restore the backup and reboot into recovery again. You're now able to use ADB due to the adbpub.key being present again. (You could've done this earlier but it's easier that way.)

Copy the rest back onto the device with "adb push / /data/media". (

I'm not really sure if this command is right, beware!

)

Now type "adb shell chown -R media_rw:media_rw /data/media" to fix issues later in the ROM.

You're basically finished now! Simply reboot and wait till it boots up again. If you're getting stuck at a "Wrong PIN" or "Wrong Pattern" screen SEE THIS COMMENT I made in another thread.

Finished!

As said, I'm not sure if I forgot something here or not. However I think I got everything covered :)