Database Users

OP2 cannot upgrade from Oxygen OS 2.2.1/Cannot flash TWRP versions newer than 3.0.2-0

So.... Pokemon Go has a lot to answer for......
I have run into a really strange problem when trying to install an OTA on my *unrooted* Oneplus 2. I have been trying to fix this for days but I have completely run out of ideas.
I originally had a working stock Oxygen 3 (Marshmallow) rom with TWRP recovery on my device (not sure of the version). The device was rooted and apart from not being able to install OTAs, I was fairly happy with the setup. Then along came the Pokemon GO update that banned rooted devices. Ok, "big deal" I thought. I was quite content playing Ingress instead (a far better game by the way that doesn't rely on a "pay to win" structure). I really wasn't too worried but then I found out about "systemless root" and "Magisk". I thought that if I installed this correctly I could still play a bit of Pokemon GO when I wanted to and could toggle a root button in Magisk Manager to install OTAs when they became available.
This is where the problems started.
I followed a guide on how to unroot and install Magisk and "Phh's Superuser". The problem was that the Phh Superuser was being denied permissions for Magisk Manager, there were no pop up notifications prompting me to give it access, just toast notifications. I couldn't for the life of me figure out how to give it permission so the "enable root" slider button kept sliding back, not allowing root. This is when I used SuperSU ver 2.76 (Magisk version) and it seemed to work fine. I now had a stock Marshmallow rom with TWRP and Magisk Manager all working exactly how they should be. I could toggle root and play Pokemon GO, then return to a rooted state when I needed to.
"Awesome, mission accomplished." I thought. Now I just need to toggle root off, download the latest OTA and install it through Flashfire.
First I made a complete nandroid backup (as I've done with other devices many times before) through TWRP. I even copied the backup folder to my PC in case something went wrong.
Well, this is when the nightmare started.
The first mistake I made was to use Flashfire when it clearly stated that Oneplus devices were currently untested. Not sure if it was a big issue or not, but it was a mistake none the less. The second mistake I made was to not stop the stock recovery being replaced when prompted before the reboot. I assumed (and it even states in the app) that the custom recovery should be reverted back to the stock recovery when attempting to apply OTA updates.
So I went ahead and rebooted, waiting for the OTA to install. I'm fairly sure from memory that it went into the stock recovery, flashed the OTA and restarted.
This is when the phone soft bricked.
"Oh well, that is why I made the backup." I thought.
I reflashed TWRP in fastboot mode and attempted to restore my backup. No dice, the phone was still soft bricked.
(And by "soft bricked" and "boot looping" I mean the Oneplus logo was in the middle of the screen, "Powered by Android" was at the bottom and the two blue LEDs for the buttons either side of the fingerprint scanner/home button remained on. This for me was the tell tale sign of the soft brick because these two light go off after a few seconds after rebooting usually.
So from here I have tried EVERYTHING. All I really want now is a working stock (rooted) Marshmallow rom with TWRP. I have downloaded many different full rom zips and attempted to flash them through TWRP with no success, I have returned to stock recovery and tried flashing signed roms with no success, I've even tried flashing the official CM13 rom for Oneplus 2 (with the correct GAPPs and kernel) through TWRP with no luck.
But here is where it gets interesting......
There are a few things that are really weird...
1. I have always been able to get into Fastboot mode and ADB and Fastboot commands "work".
* Operations succeed but don't stick (for example trying to flash TWRP versions 3.0.2-1 and 3.0.2-2 through Fastboot mode result in no recovery being there at all.
2. I can flash TWRP recovery though Fastboot mode but ONLY VERSIONS 3.0.2-0 and lower. I can also successfully flash the stock recovery.
3. I can flash OxygenOS 2.2.1 but NOT ANY VERSION RELEASED AFTER THAT. Doing so results in the soft brick "bootloop" I mentioned earlier.
4. Attempting to flash the official CM13 rom for Oneplus 2 doesn't work either. Originally I got the error 7 message, but after editing "Updater-script" in the rom and re-zipping, the process seemed to work fine in TWRP but the reboot gave me... you guessed it... a softbrick.
I have flashed custom roms on a few different devices before so I'm not a COMPLETE newbie when it comes to this stuff, but I am by no means a developer or even anything close to one. I have bricked this phone in the past (long story, involved getting it without an invite and it being shipped to me with spyware on it) but I used a guide very similar to this and it worked a treat.
www(dot)androidbrick(dot)com/unbrick-oneplus-one-two-3-qualcomm-hs-usb-qdloader-9008
So, thinking that this process would format all partitions and start me from scatch I tried it. It worked fine but I was still unable to upgrade from Oxygen OS 2.2.1 or install TWRP versions 3.0.2-1 or 3.0.2-2.
I have tried all sorts of things. I have wiped, flashed and wiped again. Factory resets, dirty flashes, clean flashes.... everything. All sorts of different sources for the TWRP images and Oxygen roms... nothing seems to work.
It's just so weird considering it's not a hard brick... just a soft brick.
So I really need my phone so I am sitting on this current build because it is the only one that works.
Here are some details of the current build I am using. (using CPU-Z app)
Model: Oneplus 2 (ONE A2001)
Android version: 5.1.1
Oxygen OS version: 2.2.1
Bootloader: Unknown
Build ID: ONE A2001_14_160226
Java VM: ART 2.1.0
OpenGL ES: 3.1
Kernel Architecture: aarch64
Kernel version: 3.10.49-perf+ (56)
Root access: Yes
Super user app: SuperSU Free v2.46 (Chainfire)
OEM unlocking: Enabled
USB debugging: Enabled
And these are some of the ZIPs and IMGs that refuse to be flashed to my device.
TWRP-3.0.2-1-oneplus2
TWRP-3.0.2-2-oneplus2
Grarak's TWRP recovery IMG for Oneplus2 (modified to install CM13) according to this guide:
missingtricks(dot)net/oneplus-2-official-cyanogenmod-13
cm-13.0-20160924-NIGHTLY-oneplus2
OnePlus2Oxygen_14_OTA_019_all_1606041303_bd42fc5cc5cc4ab2
And also my TWRP backup named 2016-09-16--09-44-09
I am really at a loss as to what to do next. ANY help ANYONE could give me would be greatly appreciated. I have been all over the net looking for ways around this bt have had no luck.
As I've said, I'm not a huge tech head, but I'm not a newbie either. The only thing I can think of is that somehow one of the partitions (maybe boot? ) may have been corrupted somehow when messing around with systemless root. But I don't know how considering it's "systemless". If anyone knows how to check for corrupted partitions on the Oneplus 2 please let me know and I'll try it. Maybe formatting these partitions might help (????), but I don't want to permanently brick my phone.
But I don't know how I've got this particular build working if one of the partitions has been corrupted. And the corrupted partition thing is just a guess.....
Please, anyone, someone point me in the right direction. Again, any and all feddback is welcomed and would be very much appreciated.
This is all Pikachu's fault.

Kamakiriash said:
A very long post...
Click to expand...
Click to collapse
The normal way too update from OOS 2 to OOS 3 is:
Flash the OOS 3 signed flashable zip via TWRP to update the bootloader and firmware
Flash TWRP 3.0.2-2 via your current TWRP's recovery image flashing option
Reboot recovery via TWRP so that you now have a recovery that's compatible with the new bootloader
Wipe data, cache & dalvik-cache (but not internal storage)
Flash the OOS 3 signed flashable zip again to update the system
Flash one of the modified SuperSU zips if you want root
Reboot system
All the files you need are in post #1 of this thread.

Thank you so much Spannaa!
I was clearly missing a vital step here and let it be a lesson to anyone else in this situation....
As Spannaa said......
1. Flash the OOS 3 signed flashable zip via TWRP to update the bootloader and firmware
2. Flash TWRP 3.0.2-2 via your current TWRP's recovery image flashing option
3. Reboot recovery via TWRP SO THAT YOU NOW HAVE A RECOVERY THAT'S COMPATIBLE WITH THE NEW BOOTLOADER!
4. Wipe data, cache & dalvik-cache (but not internal storage)
5. Flash the OOS 3 signed flashable zip AGAIN to update the system.
Again, thankyou Spanna for your quick and accurate response.
The order in which you flash zips and imgs is very important it seems.
You really saved me.
I restored the TWRP backup and I am back to where I started.
Is it now possible to apply OTAs when I toggle the root off in Magisk manager and install using the stock recovery? What do you think would be the best way to do this?
And would it be worth moving to the official build of CM13 for Oneplus 2?
Thanks again, Spannaa. :victory:

Kamakiriash said:
Thank you so much Spannaa!
I was clearly missing a vital step here and let it be a lesson to anyone else in this situation....
As Spannaa said......
1. Flash the OOS 3 signed flashable zip via TWRP to update the bootloader and firmware
2. Flash TWRP 3.0.2-2 via your current TWRP's recovery image flashing option
3. Reboot recovery via TWRP SO THAT YOU NOW HAVE A RECOVERY THAT'S COMPATIBLE WITH THE NEW BOOTLOADER!
4. Wipe data, cache & dalvik-cache (but not internal storage)
5. Flash the OOS 3 signed flashable zip AGAIN to update the system.
Again, thankyou Spanna for your quick and accurate response.
The order in which you flash zips and imgs is very important it seems.
You really saved me.
I restored the TWRP backup and I am back to where I started.
Is it now possible to apply OTAs when I toggle the root off in Magisk manager and install using the stock recovery? What do you think would be the best way to do this?
And would it be worth moving to the official build of CM13 for Oneplus 2?
Thanks again, Spannaa. :victory:
Click to expand...
Click to collapse
Glad you're sorted.
Not sure about Magisk as I've never used it.
CM13 is OK but whether it's worth you moving to it is your choice. Personally, I prefer TipsyOS!

Hi,
I face the exact issue with same Oxygen OS and TWRP versions mentioned, I have tried the above steps but there are some problems:
1. Flash the OOS 3 signed flashable zip via TWRP to update the bootloader and firmware
Click to expand...
Click to collapse
when I checked the option (Zip signature verification) in TWRP, the installation failed with error "Zip signature verification failed! Error installing zip file '/sdcard/oneplus.zip'", but it's successfully installed when I unchecked (Zip signature verification) option.
2. Flash TWRP 3.0.2-2 via your current TWRP's recovery image flashing option
3. Reboot recovery via TWRP SO THAT YOU NOW HAVE A RECOVERY THAT'S COMPATIBLE WITH THE NEW BOOTLOADER!
Click to expand...
Click to collapse
second problem is that after installing the TWRP 3.0.2-2 (or above), then reboot recovery, I can't access the recovery again and the phone stuck on bootloop.
any idea ?

Aood said:
Hi,
I face the exact issue with same Oxygen OS and TWRP versions mentioned, I have tried the above steps but there are some problems:
when I checked the option (Zip signature verification) in TWRP, the installation failed with error "Zip signature verification failed! Error installing zip file '/sdcard/oneplus.zip'", but it's successfully installed when I unchecked (Zip signature verification) option.
second problem is that after installing the TWRP 3.0.2-2 (or above), then reboot recovery, I can't access the recovery again and the phone stuck on bootloop.
any idea ?
Click to expand...
Click to collapse
I don't have a OP2 anymore but that post was seven months ago and the instructions worked for numerous users.
Don't enable zip signature verification in TWRP - it's unnecessary.
Flash TWRP 3.0.2-2 via your current TWRP's recovery image flashing option and then reboot recovery directly from TWRP.

thanx for replay Spannaa,
Flash TWRP 3.0.2-2 via your current TWRP's recovery image flashing option and then reboot recovery directly from TWRP.
Click to expand...
Click to collapse
I have already did that, but same issue once I reboot "directly from TWRP" , the TWRP doesn't show up and bootloop start again.

Aood said:
thanx for replay Spannaa,
I have already did that, but same issue once I reboot "directly from TWRP" , the TWRP doesn't show up and bootloop start again.
Click to expand...
Click to collapse
Last chance and then I'll leave this for someone that has the OP2.
Are you rebooting recovery "directly from TWRP" or rebooting system?
Is your bootloader still unlocked?

Last chance and then I'll leave this for someone that has the OP2.
Are you rebooting recovery "directly from TWRP" or rebooting system?
Is your bootloader still unlocked?
Click to expand...
Click to collapse
Yes, rebooting recovery "directly from TWRP"
and bootloader loader is unlocked,..
anyway it's not important to fix the phone, it's almost one year since last time I use it, yesterday I saw it in the drawer and try to figure out the issue..,

Trouble with booting after rooting, help.

Hello everyone, I went to root my phone today, I used a Youtube tutorial with the exact links/downloads given. Followed the steps but my device is having trouble rebooting, it is just stuck on the Samsung logo flashing and I'm not too sure what to do. Also when it boots up I get the error message in the top left of my screen saying "Recovery Is Not Seandroid Enforcing", hopefully that helps.
Thanks.

Hipp0123 said:
Hello everyone, I went to root my phone today, I used a Youtube tutorial with the exact links/downloads given. Followed the steps but my device is having trouble rebooting, it is just stuck on the Samsung logo flashing and I'm not too sure what to do. Also when it boots up I get the error message in the top left of my screen saying "Recovery Is Not Seandroid Enforcing", hopefully that helps.
Thanks.
Click to expand...
Click to collapse
Hard to help if you do not write in detail. Such as phone type, links you have used, etc etc

Hipp0123 said:
Hello everyone, I went to root my phone today, I used a Youtube tutorial with the exact links/downloads given. Followed the steps but my device is having trouble rebooting, it is just stuck on the Samsung logo flashing and I'm not too sure what to do. Also when it boots up I get the error message in the top left of my screen saying "Recovery Is Not Seandroid Enforcing", hopefully that helps.
Thanks.
Click to expand...
Click to collapse
You need to flash SuperSU manually.
1. Flash TWRP
2. Format data
3. Flash SR3-SuperSU-v2.79-SR3-20170114223742.zip
http://download.chainfire.eu/1021/SuperSU/SR3-SuperSU-v2.79-SR3-20170114223742.zip

You simply brick your phone. You need to know that there is not Chainfire-AUTO-Root for Nougat, so you need first flash Stock FIRMWARE from Sammobile, then flash TWRP and flash SuperSU
Or you can flash many of 100 roms with prerooted supersu and busybox.

Hi there,
After upgrading my S7 Edge G935F to stock version xxu1dqd7 (with latest May 2017 upgrades) I had to install TWRP (twrp-3.1.1-0-hero2lte.img) again.
Unfortunately this change will NOT recognise my pattern lock now! I had to re-install the stock image (DBT-G935FXXU1DQEF-20170523093738 with ODIN) using the HOME_CSC file to hold my data.
This re-installation brought me back to the game, but without TWRP and hope for root, but the pattern pin (the same) is now working...
Update 1
Installing TWRP (twrp-3.1.1-0-hero2lte.img) over the new stock image (DBT-G935FXXU1DQEF-20170523093738 with ODIN) without having the pattern lock enabled feature during start will result in stuck on
the samsung title.
Update 2
I had to repeat the step above (stock firmware), so stay now without root.
Will check later with other stock versions
>It seems you didn't format the data partition or dm-verity was not installed. Happened to me, won't boot if >anything is altered like when installing a custom recovery.
Yes, I did it with and without dm-verity, All 3 options,
TWRP (ok, but pattern lock will not recognized)
TWRP + supersu (2.82) (stuck on the samsung logo)
TWRP + supersu (2.82) + dm-verity (stuck on the samsung logo)
Yes, I didn'T format the data partition. Didn't want to lose my data ( Never had a problem to upgrade stock roms on my old S4 and root after).
Before the stock upgrade, I run with the Jan 2017 patch level (I bought this 2 days ago) and was able to root with the above method.
Today I wanted to jump the the latest stock version but run in trouble then.
Update 3
Downgrading to Stockrom from 2017-Jan-30 Germany 7 G935FXXU1DQB3 G935FDBT1DQA8 is not an option (anymore), The system boot up but with lot of errors and it's unresponsable and not usable.
Upgade then to the April patch status (2017-Apr-17 Germany 7 G935FXXU1DQD7 G935FDBT1DQD1) brought me back to operational,
but TWRP + supersu (2.82) + dm-verity (stuck on the samsung logo).
Will try it now with the Februar patch version
Downgrade to the Feb patch status (2017-Feb-23 Germany 7 G935FXXU1DQBX G935FOXJ1DQB2) had the same resut like the Jan version - not usable.
I'll give up now and install the April version without TWRP.
I need root to restore my apps AND data with Titanium Pro.

seppdep said:
Hi there,
After upgrading my S7 Edge G935F to stock version xxu1dqd7 (with latest May 2017 upgrades) I had to install TWRP (twrp-3.1.1-0-hero2lte.img) again.
Unfortunately this change will NOT recognise my pattern lock now! I had to re-install the stock image (DBT-G935FXXU1DQEF-20170523093738 with ODIN) using the HOME_CSC file to hold my data.
This re-installation brought me back to the game, but without TWRP and hope for root, but the pattern pin (the same) is now working...
Update 1
Installing TWRP (twrp-3.1.1-0-hero2lte.img) over the new stock image (DBT-G935FXXU1DQEF-20170523093738 with ODIN) without having the pattern lock enabled feature during start will result in stuck on
the samsung title.
Update 2
I had to repeat the step above (stock firmware), so stay now without root.
Will check later with other stock versions
>It seems you didn't format the data partition or dm-verity was not installed. Happened to me, won't boot if >anything is altered like when installing a custom recovery.
Yes, I did it with and without dm-verity, All 3 options,
TWRP (ok, but pattern lock will not recognized)
TWRP + supersu (2.82) (stuck on the samsung logo)
TWRP + supersu (2.82) + dm-verity (stuck on the samsung logo)
Yes, I didn'T format the data partition. Didn't want to lose my data ( Never had a problem to upgrade stock roms on my old S4 and root after).
Before the stock upgrade, I run with the Jan 2017 patch level (I bought this 2 days ago) and was able to root with the above method.
Today I wanted to jump the the latest stock version but run in trouble then.
Update 3
Downgrading to Stockrom from 2017-Jan-30 Germany 7 G935FXXU1DQB3 G935FDBT1DQA8 is not an option (anymore), The system boot up but with lot of errors and it's unresponsable and not usable.
Upgade then to the April patch status (2017-Apr-17 Germany 7 G935FXXU1DQD7 G935FDBT1DQD1) brought me back to operational,
but TWRP + supersu (2.82) + dm-verity (stuck on the samsung logo).
Will try it now with the Februar patch version
Downgrade to the Feb patch status (2017-Feb-23 Germany 7 G935FXXU1DQBX G935FOXJ1DQB2) had the same resut like the Jan version - not usable.
I'll give up now and install the April version without TWRP.
I need root to restore my apps AND data with Titanium Pro.
Click to expand...
Click to collapse
With the TWRP + supersu root method, no matter what 7.0 stock ROM you use, you will not succeed before you disable boot pin and format data. You can restore data after rooting.
So start with the latest stock ROM that is working 100% for you, flash twrp, format data, flash supersu, and it should work. You have to format data because root and stock rom currently does not work with encryption.
Or even simpler, use the new cf autoroot, however it seems you still have to format data.
I had high hopes that the new cf autoroot nougat binary would work with encryption, but alas it seems it doesnt, at least I had the same wrong pin code at boot issue as with twrp. I havent had time to test it, nor to format data and root, so I am currently not rooted.

doclorenzo said:
With the TWRP + supersu root method, no matter what 7.0 stock ROM you use, you will not succeed before you disable boot pin and format data. You can restore data after rooting.
So start with the latest stock ROM that is working 100% for you, flash twrp, format data, flash supersu, and it should work. You have to format data because root and stock rom currently does not work with encryption.
Or even simpler, use the new cf autoroot, however it seems you still have to format data.
I had high hopes that the new cf autoroot nougat binary would work with encryption, but alas it seems it doesnt, at least I had the same wrong pin code at boot issue as with twrp. I havent had time to test it, nor to format data and root, so I am currently not rooted.
Click to expand...
Click to collapse
Thank you doclorenzo.
I had success with the latest stock version (xxu1dqd7) and your recomendation to format data in TWRP.
In short: Boot in Download mode, Install TWRP via Odin, Boot into TWRP - format data, supersu (2.82) + dm-verity
and then restore all data. Unfortunately it requires lot of time (at least 4 hrs to restore the apps + more for fine tuning)
Thank you and hope to have a better way with the next stock update and TWRP

Galaxy j3 sm-j320zn trying to twrp???

Can anyone give me instructons on how to twrp n rot sm-j320zn ? I cant find the corrcy twrp for this model not having much luck thanks guys

koniva85 said:
Can anyone give me instructons on how to twrp n rot sm-j320zn ? I cant find the corrcy twrp for this model not having much luck thanks guys
Click to expand...
Click to collapse
Don't know if you still need the info, but I've just worked out TWRP. I've been rooted for ages but never saw your post; it's only because I decided to try TWRP again that I found you in a Google search.
TWRP that works on the J320ZN is for j3lte. To download: https://dl.twrp.me/j3lte/
Others have had issues installing SuperSU.zip in TWRP.... as did I. The only way to get root that would work is CF-Auto-Root..... because usually SuperSU.zip would then cause a bootloop. BUT of course, what I didn't realize at the time, was CF-Auto-Root once installed reflashed stock recovery! But what it DID enable me to work out (once it clicked in my head that this was going to be the issue and after I'd nearly set up my phone again) was that I was getting a dm-verity error.... something I know nothing about other than it's a new thing I have to do on my Samsung Galaxy Tab A. So MAYBE SuperSU wasn't installing because of that? Who knows.
Anyway, now I'm fully working with TWRP and root and it's sticking with no problems.
So install TWRP the usual way....(I used twrp-3.2.1-0-j3lte.img from the link above). If you need help with this quote me and ask, or look for a TWRP tutorial on j3lte (I know the J320YZ uses this TWRP and has a tutorial on how to install TWRP with Odin).
Then install the latest SuperSU.zip:
https://download.chainfire.eu/1220/SuperSU/SR5-SuperSU-v2.82-SR5-20171001224502.zip through TWRP "Install" method.... it must be on your external SD card. Go to the "Install" button on TWRP menu, select storage to extSD and then find SuperSU.zip.
THEN I had to install the Dm-verity and Forced Encryption Disabler through TWRP "Install" method (so this file also needs to be on your external SD card):
https://androidfilebox.com/miscellaneous/dm-verity-and-forced-encryption-disabler/
I used no-verity-opt-encrypt-6.0.zip
Then reboot, and reset up your phone.
FINALLY!
Whether you need to do the dm-verity thing I don't know... I'm FAR from an expert. This was all through trial and error but it is the only way to keep root through TWRP without CF-Auto-Root.....FOR ME PERSONALLY.
You could try just TWRP and the latest version of of SuperSU.zip through TWRP....see if that works. If you get stuck in a bootloop, then I just flashed CF-Auto-Root with Odin and it fixed that.... then start the install process again, this time adding dm-verity patch AFTER SuperSU.zip.
If you want to skip TWRP and just root your phone, then the easiest way is to flash CF-Auto-Root with Odin. File at https://download.chainfire.eu/986/CF...etrieve_file=1.

HELP! S8 won't boot up!

I've messed everything up and now I'm devastated!
My S8 stucks at the very first screen (where it says: SAMSUNG GALAXY S8 - powered by android). It doesn't boot further this very specific screen. I have tried to update Magisk and Magisk Manager but only Magisk Manager seems to get updated successfully while the app suddenly says that the latest version of Magisk Manager required Magisk V19.XX hence I've tried to install it via TWRP. According to log screen, I've managed to install magisk via TWRP but after booting up, I opened Magisk Manager where it now says that Magisk isn't installed. I therefore boot into TWRP and tried to fix it since some apps of mine that required root access wasn't working anymore. So, I thought I must have lost root access. I once again boot into recovery, I uninstalled magisk and install an older version of magisk and magisk manager and also the no_verity patch. After that my Galaxy S8 won't boot up. It just stucks at the very first screen. My S8 (international version) is still on Nougat stock samsung firmware and I can enter TWRP but the phone remains freeze and stubbornly refused to boot up.
I'm quite devastated and I hope you guys can help me fix this issue!
Thank you!

Hi, well sorry if I am stating the obvious but I would format and install one of the many custom roms available...

tosmaniac said:
Hi, well sorry if I am stating the obvious but I would format and install one of the many custom roms available...
Click to expand...
Click to collapse
Are there any solutions other than flashing a custom rom? Meanwhile, I have managed to flash Android 9 via ODIN and have TWRP installed but it won't boot up and stucks at the very first booting screens.
Any help would be appreciated!
Thanks!

cocolish said:
Are there any solutions other than flashing a custom rom? Meanwhile, I have managed to flash Android 9 via ODIN and have TWRP installed but it won't boot up and stucks at the very first booting screens.
Any help would be appreciated!
Thanks!
Click to expand...
Click to collapse
Have you tried just flashing stock rom only to see if it boots up. You may have to do a clean install.
Problem sounds like you haven't decrypted phone and flashed no verity zip file.
You won't need to flash a custom rom to fix this.
As for magisk have a look through this very helpful guide for installs and troubleshooting.
https://www.didgeridoohan.com/magisk/HomePage

I've managed to solve this issue by myself. But still, thank you so much! It's the thought that counts ? And yes, I've figured out that I haven't decrypt my S8. But everything is absolutely fine now and I feel extremely relieved. It took me 1 day to fix this major issue and I've encountered lots of difficulties while trying to fix this like bootloops, system won't boot up and managed to stuck at the very first booting screen again and the phone boot past the first booting screen and stucks at the second booting screen, and also bootloader error and stuffs like where realization hit me that I can't restore my nandroid backup while still on Nougat because after restoring it won't boot up. I therefore managed to flash Android 9 and twrp. My S8 is now on Android Pie with custom recovery and rooted (via Magisk).

Lost root access and can't get it back via Magisk. Help!

Galaxy S8 Exynos [SM-G950FD] Android Oreo 8.0.0
Hello. it's my first time posting here. So I've had a successful attempt at flashing TWRP and Magisk into my phone. Today I accidentally plugged in my charger while it was in the process of rebooting, so it entered my device into kind of a bootloop. I solved this by going into Download Mode and pressing 'Cancel', which prompted my device to successfully reboot and work again.
The problem is that I've somehow lost my root. None of my apps can get root access, CPU-Z says no root available, and Magisk Manager said "Magisk is not installed". Idk how I got to this because yesterday all was working, I assume it's because I got a bootloop or went into Download Mode.
I tried to install the official Magisk ZIP file from the Manager, go into recovery mode, and flash it via TWRP. Unfortunately this didn't work. This is the only solution I can come up with besides reflashing Stock and having to flash Magisk again and wipe all my current data. If anyone has any suggestions please comment down below as I'm kinda stuck rn. They would be greatly appreaciated!

bigbraintime said:
Galaxy S8 Exynos [SM-G950FD] Android Oreo 8.0.0
Hello. it's my first time posting here. So I've had a successful attempt at flashing TWRP and Magisk into my phone. Today I accidentally plugged in my charger while it was in the process of rebooting, so it entered my device into kind of a bootloop. I solved this by going into Download Mode and pressing 'Cancel', which prompted my device to successfully reboot and work again.
The problem is that I've somehow lost my root. None of my apps can get root access, CPU-Z says no root available, and Magisk Manager said "Magisk is not installed". Idk how I got to this because yesterday all was working, I assume it's because I got a bootloop or went into Download Mode.
I tried to install the official Magisk ZIP file from the Manager, go into recovery mode, and flash it via TWRP. Unfortunately this didn't work. This is the only solution I can come up with besides reflashing Stock and having to flash Magisk again and wipe all my current data. If anyone has any suggestions please comment down below as I'm kinda stuck rn. They would be greatly appreaciated!
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Check out this guide. It may be of some use
https://www.didgeridoohan.com/magisk/HomePage

spawnlives said:
Check out this guide. It may be of some use]
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Thanks. I tried the methods listed in the "Lost root randomly" section and unfortunately they didnt work. Do you have any other ideas? Maybe I could "Select and Patch a File" in Magisk's Install but afaik Magisk doesnt have its img./tar. file.
I should probably just flash a fresh stock and redo the root process, but then my data will be wiped and I dont really want that lol

bigbraintime said:
Thanks. I tried the methods listed in the "Lost root randomly" section and unfortunately they didnt work. Do you have any other ideas? Maybe I could "Select and Patch a File" in Magisk's Install but afaik Magisk doesnt have its img./tar. file.
I should probably just flash a fresh stock and redo the root process, but then my data will be wiped and I dont really want that lol
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Have you tried the uninstaller through magisk or twrp then try again with magisk.
When trying to re-install magisk do you get any errors.
https://github.com/topjohnwu/Magisk/releases
Also if worried about losing apps/data do a backup before trying anything.
The easiest way is to flash firmware and start from scratch again but backup first.