[HTC 10 ROMs, Kernels, Recoveries, & Other Developm] nkk71:
this is my personal experience, largely based on [MENTION=1162986]Captain_Throwback[/MENTION] excellent write-up from previously

I just did a few steps different (but in essence the same principle), and just to keep the "definitions" proper and short:

* OTA OK means i get the notification and am able to download it, no "system error"

* Radio OK means, I had no signal loss whatsoever

* SuperSU OK means systemless SuperSU is functioning properly

when saying "Boot into TWRP" it's implied that you: cancel decryption prompt & leave system read-only on boot!!

And now exactly what I did:

1) Unlock bootloader via HTC Dev -> wipes device

2) Reboot System -> encryption will kick in -> Android is starting... optimizing app y of z

OTA OK , Radio OK

3) Flash TWRP in download mode ("fastboot flash recovery twrp-3.0.2-2-pme.img")

Optional but highly recommended:

4) Boot into TWRP (as mentioned above cancel decryption, and keep system read-only)

5) Backup "Boot" and "System Image" in TWRP to External SD

6) Boot System, and copy backup to PC

OTA OK, Radio OK

7) Boot into TWRP (as mentioned above cancel decryption, and keep system read-only)

* In adb shell or TWRP Terminal, echo KEEPFORCEENCRYPT=true>>/cache/.supersu EDIT: I dont think that's actually needed in this particular case, my device is still encrypted from the above steps, so I dont actually need to forceencrypt EDIT2: actually I do need forceencrypt for sunshine later on.

* Install BETA-SuperSU 2.72 from external SD card

* Reboot back to System, the device will auto-reboot once, which is needed by systemless SuperSU installs

OTA OK, Radio OK, SuperSU OK

8)

Optional

SunShine S-OFF:

install sunshine.apk

run app, test, pay, final test, continue

reboot splash, reboot splash

.

reboot system -> it will ask for decryption ... due to the change in "phone status" the data partition is no longer "recognized" ... DO NOT TRY TO DECRYPT

.

press POWER and select restart, then press and hold volume down, during reboot, to get to download mode

.

you'll see the device is now S-OFF

.

Since data is no longer "recognized" properly. boot back into TWRP

(since you're in download mode go to bootloader from there you can go to recovery)

and -> Wipe -> Format Data

.

Reboot System -> encryption will kick in -> Android is starting... optimizing app y of z

OTA OK, Radio OK

obviously no more SuperSU, we just formatted the device

9) Back to TWRP -> install BETA-SuperSU 2.72

(nothing in cache, so no forceencrypt [i'm already encrypted from previously above], no verity)

OTA OK, Radio OK, SuperSU OK

10) Back to TWRP and restore "System Image" (i did not restore boot or anything else... so this still has the SuperSU modified boot.img)

(the one from part (5) above or if you have a proper untouched one downloaded from someone else)

11) Restore stock recovery (which I got from the OTA) "fastboot flash recovery stock_recovery_1.30.401.1.img"

12) Reboot to System

OTA OK, Radio OK, SuperSU OK

13) Download and install OTA (in my case from 1.21.401.4 to 1.30.401.1)

Which worked fine.... I obviously lost TWRP (replaced by new stock recovery), and SuperSU (though the apk still shows) (replaced by the new boot.img), but that's minor.... the OTA downloaded and installed just fine without any complaints.

Hope this helps, and alleviate some of the drama and speculation going on... i just did this today, and it worked fine.