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phone boots into bootloader mode, even with a fresh rom flash??

Hi. i need some help.
I have a huge problem regarding getting my one plus 6 back up and running.
Here is what i did.
Downloaded a rom, gapps and magisk.
wipe in twrp, install, rom, gapps. worked fine, booted up rom.
when i flashed the lastest version of magisk, it boots into bootloader.
Then i did a DATA wipe. start a fresh boot.
*booted twrp via adb.
* pushed, rom, gapps, twrp into sdcard.
* installed, rom, twrp, gapps. reboot.
goes directly into boot loader.
WHAT DO I DO? my phone is screwed.
EDIT: Room bug. nothing wrong with phone or recovery. just bug in the rom.

saitek1911 said:
Hi. i need some help.
I have a huge problem regarding getting my one plus 6 back up and running.
Here is what i did.
Downloaded a rom, gapps and magisk.
wipe in twrp, install, rom, gapps. worked fine, booted up rom.
when i flashed the lastest version of magisk, it boots into bootloader.
Then i did a DATA wipe. start a fresh boot.
*booted twrp via adb.
* pushed, rom, gapps, twrp into sdcard.
* installed, rom, twrp, gapps. reboot.
goes directly into boot loader.
WHAT DO I DO? my phone is screwed.
Click to expand...
Click to collapse
Wipe all.
Boot to twrp
flash ROM
Reboot twrp
For flash gapps
Boot to ROM
Setup and enjoy

DaveHTC200 said:
Wipe all.
Boot to twrp
flash ROM
Reboot twrp
For flash gapps
Boot to ROM
Setup and enjoy
Click to expand...
Click to collapse
already done this. twice. still goes into bootloader on every boot.

saitek1911 said:
already done this. twice. still goes into bootloader on every boot.
Click to expand...
Click to collapse
Save everything from SD card to PC and try with:
fastboot -w
Then just try installing ROM
And rebooting to it.
Worry about gapps etc after,.
Possibly bad download too

Did you try booting into the other partition. A/B?

Use magisk 16.4 and then you can update thro the app. 16.7 has a flash bug

From seeing him in another thread I think he got it

saitek1911 said:
already done this. twice. still goes into bootloader on every boot.
Click to expand...
Click to collapse
when a wipe does not get it working, then ( sadly ) go to the next step of "format data", but "BACKUP" stuff you want to keep ( ie. /storage/emulated/0/Download ) to pc first . . .
( it's what I had to do )

Same issue here...
Tried to fromat data but still boot into fastboot.
Rom: Havoc

saitek1911 said:
Hi. i need some help.
I have a huge problem regarding getting my one plus 6 back up and running.
Here is what i did.
Downloaded a rom, gapps and magisk.
wipe in twrp, install, rom, gapps. worked fine, booted up rom.
when i flashed the lastest version of magisk, it boots into bootloader.
Then i did a DATA wipe. start a fresh boot.
*booted twrp via adb.
* pushed, rom, gapps, twrp into sdcard.
* installed, rom, twrp, gapps. reboot.
goes directly into boot loader.
WHAT DO I DO? my phone is screwed.
EDIT: Room bug. nothing wrong with phone or recovery. just bug in the rom.
Click to expand...
Click to collapse
Had the same problem, boot to temporary TWRP with the fastboot command "fastboot boot <twrp img>", wipe /system and then try flashing stock ROM via fastboot, it worked for me, hope it helps. Good luck! :good:

Oneplus 7 Pro can install updates anymore

Hello xda-comunity
I'm unable to install the oxygenos update 9.5.8 GM21BA
So I was following this guide to unlock my bootloader and root my phone with magisk.
( https://www.google.com/amp/s/www.xda-developers.com/unlock-bootloader-root-oneplus-7-pro/amp/ )
All went well. I got the notification that there is a new update (see above)
In the guide there was a step - by - step instruction on how to update the phone and keep root. I did that.
And now when try to install the update I get a bootloop into recovery. I figured out that the op7pro is a 2 slot phone ( slot a, slot b) and when I install a update it sets the for example slot b (where the update is installed) as default.
So when something goes wrong it just loads up the "previous" slot (in this example slot a) as default again and says that the update failed to install. Correct me if I'm wrong .
And now to the my problem, the phone doesn't load on slot b nor does it default back to slot a, instead I get a recovery bootloop when I'm in slot b.
The fix here is to flash twrp via fastboot and load slot a again, my phone then boots up like normal.
And here is the problem I can't install the update because I probably messed up slot b.
I know it's a long post and I appreciate every possible answer. Thanks in advance.

Wipe Data, Dalvik.
Flash the OTA, TWRP Installer.
Reboot to Recovery.
Flash the ROM, TWRP Installer again.
Reboot to Recovery.
Flash Magisk and other zips like roms or kernels
Reboot system
This will install on both slots

whatthekj said:
Wipe Data, Dalvik.
Flash the OTA, TWRP Installer.
Reboot to Recovery.
Flash the ROM, TWRP Installer again.
Reboot to Recovery.
Flash Magisk and other zips like roms or kernels
Reboot system
This will install on both slots
Click to expand...
Click to collapse
Thanks for the quick response I will try that as soon as I'm home from work. How do I find the ota? Can I download it? Or is it saves in a folder on the phone? Because I downloaded it like 3 times now.

jollyjumper2000 said:
Thanks for the quick response I will try that as soon as I'm home from work. How do I find the ota? Can I download it? Or is it saves in a folder on the phone? Because I downloaded it like 3 times now.
Click to expand...
Click to collapse
Use this thread https://forum.xda-developers.com/oneplus-7-pro/how-to/oneplus-7-pro-global-repo-oxygen-os-t3930585 and download the correct OTA for your phone. Copy it to the root of your phone then flash it in TWRP and follow the steps I gave you.

whatthekj said:
Wipe Data, Dalvik.
Flash the OTA, TWRP Installer.
Reboot to Recovery.
Flash the ROM, TWRP Installer again.
Reboot to Recovery.
Flash Magisk and other zips like roms or kernels
Reboot system
This will install on both slots
Click to expand...
Click to collapse
On step 3 do I need to flash the rom new? even tho if i keep it stock? or do you mean the ota?

jollyjumper2000 said:
On step 3 do I need to flash the rom new? even tho if i keep it stock? or do you mean the ota?
Click to expand...
Click to collapse
Sorry I worded that oddly.
If you want to keep it stock then:
Wipe Data (Optional but recommended), Dalvik.
Flash the OTA, TWRP Installer.
Reboot to Recovery.
Flash the OTA, TWRP Installer again.
Reboot to Recovery.
Flash Magisk and/or kernels (Step is optional)
Reboot system
If youre installing a custom ROM like Havoc then:
Wipe Data, Dalvik.
Flash the OTA, ROM then TWRP Installer.
Reboot to Recovery.
Flash the ROM, TWRP Installer again.
Reboot to Recovery.
Flash GApps and Magisk (Step is optional)
Reboot system

whatthekj said:
Sorry I worded that oddly.
If you want to keep it stock then:
Wipe Data (Optional but recommended), Dalvik.
Flash the OTA, TWRP Installer.
Reboot to Recovery.
Flash the OTA, TWRP Installer again.
Reboot to Recovery.
Flash Magisk and/or kernels (Step is optional)
Reboot system
If youre installing a custom ROM like Havoc then:
Wipe Data, Dalvik.
Flash the OTA, ROM then TWRP Installer.
Reboot to Recovery.
Flash the ROM, TWRP Installer again.
Reboot to Recovery.
Flash GApps and Magisk (Step is optional)
Reboot system
Click to expand...
Click to collapse
No need to say sorry i´m so greatful for your help.
thanks again

whatthekj said:
Sorry I worded that oddly.
If you want to keep it stock then:
Wipe Data (Optional but recommended), Dalvik.
Flash the OTA, TWRP Installer.
Reboot to Recovery.
Flash the OTA, TWRP Installer again.
Reboot to Recovery.
Flash Magisk and/or kernels (Step is optional)
Reboot system
If youre installing a custom ROM like Havoc then:
Wipe Data, Dalvik.
Flash the OTA, ROM then TWRP Installer.
Reboot to Recovery.
Flash the ROM, TWRP Installer again.
Reboot to Recovery.
Flash GApps and Magisk (Step is optional)
Reboot system
Click to expand...
Click to collapse
Ok so I flashed the ota and twrp installer and rebooted into recovery
but now I cant find the ota and twrp installer files in the root folder. Maybe bec I´m on slot b now?
I dont know how to flash it the second time
Can i flash it from ADB on the PC? Because i flashed it from twrp. when yes what are the commands for it?

jollyjumper2000 said:
Ok so I flashed the ota and twrp installer and rebooted into recovery
but now I cant find the ota and twrp installer files in the root folder. Maybe bec I´m on slot b now?
I dont know how to flash it the second time
Can i flash it from ADB on the PC? Because i flashed it from twrp. when yes what are the commands for it?
Click to expand...
Click to collapse
You can drag the files back into the root of your phone and flash them on the other slot. You could ADB fastboot but just dragging the zips to your phone is easier in my opinion.

whatthekj said:
You can drag the files back into the root of your phone and flash them on the other slot. You could ADB fastboot but just dragging the zips to your phone is easier in my opinion.
Click to expand...
Click to collapse
Sorry if Iam stupid but is that how it works?
I flash the zips on slot a then reboot to boot into slot b to flash it there again?
Because I dont get it, am I missing something here?
Edit: Seems like I Bootloop into recovery on slot b.

jollyjumper2000 said:
Sorry if Iam stupid but is that how it works?
I flash the zips on slot a then reboot to boot into slot b to flash it there again?
Because I dont get it, am I missing something here?
Edit: Seems like I Bootloop into recovery on slot b.
Click to expand...
Click to collapse
Yes you flash on both slots. If youve already flashed both then flash magisk and reboot to system. It should take about 10min to boot so dont worry.
Edit: If youre getting a bootloop or having bugs then follow this https://forum.xda-developers.com/oneplus-7-pro/how-to/rom-stock-f to get back to stock international
Then follow https://forum.xda-developers.com/on...nt/recovery-unofficial-twrp-recovery-t3931322 then flash Magisk and reboot
This is ONLY if you cannot get it to boot after updating

whatthekj said:
Yes you flash on both slots. If youve already flashed both then flash magisk and reboot to system. It should take about 10min to boot so dont worry.
Click to expand...
Click to collapse
Ok but how do i do that when slot b is empty?
I dont know how to put files on slot b.
When I switch slots I have to reboot.
I can only boot into system on slot a.

whatthekj said:
Yes you flash on both slots. If youve already flashed both then flash magisk and reboot to system. It should take about 10min to boot so dont worry.
Edit: If youre getting a bootloop or having bugs then follow this https://forum.xda-developers.com/oneplus-7-pro/how-to/rom-stock-f to get back to stock international
Then follow https://forum.xda-developers.com/on...nt/recovery-unofficial-twrp-recovery-t3931322 then flash Magisk and reboot
This is ONLY if you cannot get it to boot after updating
Click to expand...
Click to collapse
Your link gets me to the front page of the Oneplus 7 pro Guides, News, etc....

It should've taken you to the Fastboot thread. Look at this one instead https://forum.xda-developers.com/oneplus-7-pro/how-to/rom-stock-fastboot-roms-oneplus-7-pro-t3931424

Alright i flashed the ROM new
Was able to install the newest ota just perfect.
Kept it unrooted, I think I'm gonna let it unrooted because of all the work I have to do Everytime a new ota comes (maybe later when the phone is older)
Thank you so much for your help.

OnePlus 7 Pro Flashing doesn't work properly

Hey guys,
so first of all I wanna let you know that my device is not bricked or something (it was a couple of times though).
But let's get started with my issue. For me, personally, I have experienced that the slot system (A/B Slot) doesn't work that good. I had a OnePlus 3T before and I never had any problems with flashing, but now...
My impression is that it's a lot easier to brick its' device than before. Every time I want to flash a new OS I gotta use the msmtool.
1. I boot to recovery mode through the OS
2. I boot to fastboot trough the OOS stock recovery
3. I try to flash TWRP to erase the system
4. Flashing works, but I can no longer boot into recovery mode
5. I have a bootloop (fastboot mode only)
6. I have to use that msmtool
7. I have some old OOS (9.5.5 or something)
8. I unlock the bootloader through the OS & fastboot
9. I boot into TWRP, delete everything and flash another ROM
10. Everything works and the cicle begins again​
I really don't know why I'm always stuck in that bootloop... Maybe you guys could help me and give me your personal opinion on the slot system?

I totally know that feeling. I started with a tmo op7p, flashed international, unlocked bootloader, try to boot TWRP, and nope. Switch slot, it works. Flash it, great. Make a backup with TWRP of my working system, flash ROMaur, won't do anything but boot to TWRP. Open TWRP file manager and every file on internal storage is a ton of folders with jumbled strings of letters and numbers for names. MSM tool back to intl stock, try lineage... Nope. Keeps telling me to do a factory reset. I did, but I do another and still boot loop. MSM to intl, try other roms, same outcome.
I can unlock my bootloader and root it and run intl stock but that's it.

oxadedzn said:
Hey guys,
so first of all I wanna let you know that my device is not bricked or something (it was a couple of times though).
But let's get started with my issue. For me, personally, I have experienced that the slot system (A/B Slot) doesn't work that good. I had a OnePlus 3T before and I never had any problems with flashing, but now...
My impression is that it's a lot easier to brick its' device than before. Every time I want to flash a new OS I gotta use the msmtool.
1. I boot to recovery mode through the OS
2. I boot to fastboot trough the OOS stock recovery
3. I try to flash TWRP to erase the system
4. Flashing works, but I can no longer boot into recovery mode
5. I have a bootloop (fastboot mode only)
6. I have to use that msmtool
7. I have some old OOS (9.5.5 or something)
8. I unlock the bootloader through the OS & fastboot
9. I boot into TWRP, delete everything and flash another ROM
10. Everything works and the cicle begins again
I really don't know why I'm always stuck in that bootloop... Maybe you guys could help me and give me your personal opinion on the slot system?
Click to expand...
Click to collapse
Doing it wrong.
If you are currently rooted and a new OS comes out you can do the following and you don't need to flash with TWRP or use a computer.
1. Download the full OTA. You can use Oxygen updater to do that or use a link in the stock ROM section on this site.
2. Make sure you have the Magisk and the TWRP zip on the phone.
3. Do a local update in the system area but do not reboot.
4. Launch Magisk manager and select install.
5. Use the OTA install option to inactive slot.
6. Now you can reboot. You have installed the new OS and root also.
7. Once rebooted do another local install. This will install in the slot that you were just running. It will fail the first time, but work the second time.
8. Repeat 4.
9. Repeat 5.
10 . Repeat 6.
You now have both slots with the same OS and rooted.
If you want to install TWRP.
Launch Magisk and install the TWRP zip.
Reboot into recovery. This is important because you cannot boot in slot with TWRP unless Magisk in installed.
Now flash the Magisk image file.
Now in TWRP select the other slot and reboot into recovery.
In recovery install Magisk image to this slot.
Now you have TWRP and Magisk in both slots.
I have done it that way since 9.5.7 and have not had an issue.

tech_head said:
Doing it wrong.
If you are currently rooted and a new OS comes out you can do the following and you don't need to flash with TWRP or use a computer.
1. Download the full OTA. You can use Oxygen updater to do that or use a link in the stock ROM section on this site.
2. Make sure you have the Magisk and the TWRP zip on the phone.
3. Do a local update in the system area but do not reboot.
4. Launch Magisk manager and select install.
5. Use the OTA install option to inactive slot.
6. Now you can reboot. You have installed the new OS and root also.
7. Once rebooted do another local install. This will install in the slot that you were just running. It will fail the first time, but work the second time.
8. Repeat 4.
9. Repeat 5.
10 . Repeat 6.
You now have both slots with the same OS and rooted.
If you want to install TWRP.
Launch Magisk and install the TWRP zip.
Reboot into recovery. This is important because you cannot boot in slot with TWRP unless Magisk in installed.
Now flash the Magisk image file.
Now in TWRP select the other slot and reboot into recovery.
In recovery install Magisk image to this slot.
Now you have TWRP and Magisk in both slots.
I have done it that way since 9.5.7 and have not had an issue.
Click to expand...
Click to collapse
Irrelevant ISH, but ever had that one bootloop where it only bootloops at the "Warning Bootloader unlocked screen" constantly? When I try to access fastboot, it'll just go straight to recovery without even waiting for input (to my luck, of course, until I had to uninstall magisk in full, reinstall, make sure TWRP was reflashed and did the "Fix recovery bootloop", though that wasn't the seemingly the issue). The issue got resolved, but it was very scary for that to have happened as soon as i enabled sudohide (I always had it work, but with huge problems, but never enough to bootloop me to death)

JhinCuatro said:
Irrelevant ISH, but ever had that one bootloop where it only bootloops at the "Warning Bootloader unlocked screen" constantly? When I try to access fastboot, it'll just go straight to recovery without even waiting for input (to my luck, of course, until I had to uninstall magisk in full, reinstall, make sure TWRP was reflashed and did the "Fix recovery bootloop", though that wasn't the seemingly the issue). The issue got resolved, but it was very scary for that to have happened as soon as i enabled sudohide (I always had it work, but with huge problems, but never enough to bootloop me to death)
Click to expand...
Click to collapse
If you install TWRP on a 7 Pro without installing Magisk you will absolutely boot loop. If you wipe the system in one slot and have a differing ROM from the active slot you can in fact boot loop. Although the systems are different, the settings between the systems are shared.

Sorry to say, but nothing about those steps is correct. Follow some guides in the guides section to get aquatinted with the A/B system

Arden144 said:
Sorry to say, but nothing about those steps is correct. Follow some guides in the guides section to get aquatinted with the A/B system
Click to expand...
Click to collapse
You are absolutely incorrect.
When going from 9.5.10 to 9.5.11 and all my previous upgrades it has been:
1. Local install of the new OS with a full OTA since I am rooted.
2. Do not reboot.
3. Install Magisk to inactive slot.
4. Reboot (Slot will automatically switch to the one recently updated).
5. Local install of OS into the other slot, fails first time, do it again.
6. Install Magisk into inactive slot.
7. Reboot. (Slot will switch to recently updated slot).
8. Both slots now have latest OS and are rooted.
You can also install TWRP if you like.
No computer needed.
This works.

tech_head said:
You are absolutely incorrect.
When going from 9.5.10 to 9.5.11 and all my previous upgrades it has been:
1. Local install of the new OS with a full OTA since I am rooted.
2. Do not reboot.
3. Install Magisk to inactive slot.
4. Reboot (Slot will automatically switch to the one recently updated).
5. Local install of OS into the other slot, fails first time, do it again.
6. Install Magisk into inactive slot.
7. Reboot. (Slot will switch to recently updated slot).
8. Both slots now have latest OS and are rooted.
This works.
Click to expand...
Click to collapse
That's completely unnecessary and just avoiding the purpose of the a/b system.
All it would take is:
1. Local install
2. Install magisk to inactive slot

what am I doing wrong?

So I'm bootloader unlocked for 10.0.0.1 I'm about to update to 10.0.3.
Everytime I try to flash recovery or boot recovery with twrp it doesn't work.
If I load it via magisk it works sometime but other times causes bootloops.
My biggest issue is booting/flashing twrp and When I flash a custom rom.
It says to flash on A and B. Sometime I can flash to one but when u change to other slot it wolnt flash or it'll show like it's encrypted any help? I've been on basic OS with NoLimits but now I wanna do kernel, rom flashing etc. Help?

If you want to update from .1 to .3 just do this(keeping in mind that you already had twrp and magisk)
Put update.zip in your internal storage
Go to settings>system>updates>local upgrade
Select update and install
Wait to finish but DONT REBOOT
go to magisk and install twrp installer(I use V3.3.1-74)
Then install magisk to inactive slot(after ota)
Reboot and that's it!
You can install custom kernel from twrp or fk kernel or any other app
If you want to install a rom you had to install to both slots(keep in mind that ROMs always be installed on inactive slot)
So make a factory reset(default by twrp wipes data and dalvik)
Install your rom and don't reboot(example if you are on A slot it will be installed to B)
Install twrp installer
Reboot to recovery( this will change slots A to B for example)
Install your rom (slot B to A and you will have your rom in both slots right?)
Again install twrp installer
Reboot to recovery
Flash gapps( if rom don't have it) magisk and kernel I personally recommend to flash after first boot
EDIT:
And another thing, if you get your internal storage encrypted and you can't access your rom,gapps,magisk you can always use adb sideload:
In your platform tools folder put your rom,magisk, etc and in twrp go to advanced>adb sideload and swipe to initiate.
In your command window use this:
adb sideload <nameofyourfile.zip>
Example: adb sideload magisk.zip
This will transfer and install magisk, ROMs and gapps
Sent from my OnePlus7Pro using XDA Labs

Here's the hinge on the rom right? Install on slot in recovery OK good got it. Reboot recovery try to install on other slot there is nothing on phone or its encrypted.

Android 10 & Custom ROM & Slot A + B

Hello Android developers and enthusiasts,
I've been installing ROM since 2011 so I would not call myself a n00b however I seemingly cannot install an Android 10 ROM without issues. So this is a plea for help and advice!
I know you need to have OOS installed before you install a custom ROM so I use Auto Flash ROM to install OOS with Android 9 via System Update. I then boot and set up phone, install update, reboot and then install the OOS android 10 via the System Update. I then have a OOS installed with Android 10.
Why would I use such an elaborate method you may ask? Well, I tried to download latest OOS from OnePlus site and wipe phone and then install OOS but that fails (didn't record the error I'm afraid).
I then download all the ROM + dependencies on an USB stick and use fastboot to flash Mauronofrio TWRP. I then follow the steps in the ROM instructions. For EvolutionX these were:
First Time Install / Clean Flash
- Have OOS 10.3 flashed to both slots!!
- Boot to recovery
- Flash BUILD.zip (TWRP built-in)
- Wipe Cache
- Format data
- Reboot to recovery (optional)
- Flash Magisk.zip (optional)
- Reboot to system & #KeepEvolving
Click to expand...
Click to collapse
I followed these to the letter but when i rebooted system I got a snapdragon error and it wouldn't even boot into TWRP until I used fastboot to flash boot into TWRP. I also tried HavocROM and same happened.
I did manage to install Syberia using above method but I didn't like the ROM that much unfortunately.
Finally, I've also read up a lot on Slot A and B but it still is not very clear to me. I think I understand it but what happens does not confirm my theories
I therefore have some questions:
- Should I be able to wipe my phone and install OOS on a wiped phone and then install a custom ROM?
- When I install ROM and it says "Reboot Recovery" and then install ROM again. But if I check what slot is being used the reboot doesn't seem to change the slot. My assumption was that booting recovery was to install ROM in the other slot. Is that correct?
Any other tips you can give me?
Again, I like to stress I am not new to installing custom ROMs so I am a bit disappointed that this is causing me such grief.
Following some answers I will retry tomorrow so I can give some more details if needed. For now, appreciate any help.

roel1976 said:
Hello Android developers and enthusiasts,
I've been installing ROM since 2011 so I would not call myself a n00b however I seemingly cannot install an Android 10 ROM without issues. So this is a plea for help and advice!
I know you need to have OOS installed before you install a custom ROM so I use Auto Flash ROM to install OOS with Android 9 via System Update. I then boot and set up phone, install update, reboot and then install the OOS android 10 via the System Update. I then have a OOS installed with Android 10.
Why would I use such an elaborate method you may ask? Well, I tried to download latest OOS from OnePlus site and wipe phone and then install OOS but that fails (didn't record the error I'm afraid).
I then download all the ROM + dependencies on an USB stick and use fastboot to flash Mauronofrio TWRP. I then follow the steps in the ROM instructions. For EvolutionX these were:
I followed these to the letter but when i rebooted system I got a snapdragon error and it wouldn't even boot into TWRP until I used fastboot to flash boot into TWRP. I also tried HavocROM and same happened.
I did manage to install Syberia using above method but I didn't like the ROM that much unfortunately.
Finally, I've also read up a lot on Slot A and B but it still is not very clear to me. I think I understand it but what happens does not confirm my theories
I therefore have some questions:
- Should I be able to wipe my phone and install OOS on a wiped phone and then install a custom ROM?
- When I install ROM and it says "Reboot Recovery" and then install ROM again. But if I check what slot is being used the reboot doesn't seem to change the slot. My assumption was that booting recovery was to install ROM in the other slot. Is that correct?
Any other tips you can give me?
Again, I like to stress I am not new to installing custom ROMs so I am a bit disappointed that this is causing me such grief.
Following some answers I will retry tomorrow so I can give some more details if needed. For now, appreciate any help.
Click to expand...
Click to collapse
Hi!
I had this exact same problem a couple months ago. Rebooting to recovery used to change slots for me, but then it stopped.
What you can do is change active slot manually on Reboot section. By doing this, you don't even have to reboot to recovery in other to flash the other slot (altough I do it just to be safe).
And remember: the rom is flashed on the inactive slot, so after the final flash you gotta change slots one more time.

When you flash one ROM on top of another different ROM, particularly OOS to custom, always wipe data and not format data, because some custom ROMs do not support being unencrypted in the first time and then encrypt on the first boot. So do it like this:
Flash OOS
Flash TWRP
Reboot recovery
Flash OOS
Flash TWRP
Reboot system
Complete initial setup
Reboot to recovery
Wipe (not format) data
Flash custom ROM (start here for dirty flashing ROM update)
Flash TWRP
Reboot recovery
Flash custom ROM
Flash TWRP
Reboot recovery
Flash Magisk
Reboot system
I don't like built-in TWRP in custom ROMs. I always use @mauronofrio's TWRP. So regardless if the custom ROM I'm using has TWRP built-in or not, I always use the method above. I didn't have a problem with installing ROMs using his TWRP. Slots always switch when flashing ROM.

Thanks for the info, it really helps.
One question: in your experience can you wipe your phone and then installl OOS on the wiped phone?

So I just booted into TWRP, did standard wipe action: Data, Cache, and Dalvik. I then try to flash the latest OOS zip and I then get this error:
Error applying update: 7 (ErrorCode::kInstallDeviceOpenError)
Updater process ended withL ERROR: 1.
Error installing zip file: '/usbstorage/00, INSTALL/OnePlus6Oxygen_22_OTA_044_all_2002220042_a46425f1bfe43d2.zip
FIXED: I was using TWRP 3.3.1.11 and I then found out there was a newer version: 3.3.1.18 which you can get here: https://sourceforge.net/projects/mauronofrio-twrp/files/Enchilada/
I am now able to install OOS from scratch (ie wiped phone).

remewer said:
When you flash one ROM on top of another different ROM, particularly OOS to custom, always wipe data and not format data, because some custom ROMs do not support being unencrypted in the first time and then encrypt on the first boot. So do it like this:
Flash OOS
Flash TWRP
Reboot recovery
Flash OOS
Flash TWRP
Reboot system
Complete initial setup
Reboot to recovery
Wipe (not format) data
Flash custom ROM (start here for dirty flashing ROM update)
Flash TWRP
Reboot recovery
Flash custom ROM
Flash TWRP
Reboot recovery
Flash Magisk
Reboot system
I don't like built-in TWRP in custom ROMs. I always use @mauronofrio's TWRP. So regardless if the custom ROM I'm using has TWRP built-in or not, I always use the method above. I didn't have a problem with installing ROMs using his TWRP. Slots always switch when flashing ROM.
Click to expand...
Click to collapse
I tried this method and everytime I can't seem to flash oos onto the other slot because when it reboots to recovery the folder is encrypted so I can't see which file is the zip. How do I flash the seccond OOS if it shows up encrypted in TWRP.
I have a OnePLus 6 with the latest OOS now because I got into boot loop and i used a flash-all.bat to get back to stock. I also use maronofrio's twrp because that works.

harshybar said:
I tried this method and everytime I can't seem to flash oos onto the other slot because when it reboots to recovery the folder is encrypted so I can't see which file is the zip. How do I flash the seccond OOS if it shows up encrypted in TWRP.
I have a OnePLus 6 with the latest OOS now because I got into boot loop and i used a flash-all.bat to get back to stock. I also use maronofrio's twrp because that works.
Click to expand...
Click to collapse
If you can boot OOS fine, try to do a local update so that both slots have OOS. Then try to flash a custom ROM again using the method I've mentioned.

remewer said:
If you can boot OOS fine, try to do a local update so that both slots have OOS. Then try to flash a custom ROM again using the method I've mentioned.
Click to expand...
Click to collapse
When you say local update you mean while I am running the rom, go to settings then do update from local source?

harshybar said:
When you say local update you mean while I am running the rom, go to settings then do update from local source?
Click to expand...
Click to collapse
Exactly

GuestD2559 said:
When you flash one ROM on top of another different ROM, particularly OOS to custom, always wipe data and not format data, because some custom ROMs do not support being unencrypted in the first time and then encrypt on the first boot. So do it like this:
Flash OOS
Flash TWRP
Reboot recovery
Flash OOS
Flash TWRP
Reboot system
Complete initial setup
Reboot to recovery
Wipe (not format) data
Flash custom ROM (start here for dirty flashing ROM update)
Flash TWRP
Reboot recovery
Flash custom ROM
Flash TWRP
Reboot recovery
Flash Magisk
Reboot system
I don't like built-in TWRP in custom ROMs. I always use @mauronofrio's TWRP. So regardless if the custom ROM I'm using has TWRP built-in or not, I always use the method above. I didn't have a problem with installing ROMs using his TWRP. Slots always switch when flashing ROM.
Click to expand...
Click to collapse
@Cypher_01, Try this guide. This worked for me. I did not reinstall Nikgapps. Maybe that's where the problem lies? Don't forget to change the update slot at the end before you restart.​