Question Why are custom ROMs bricking my device?

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Hello everyone, I have the OP9 china varient,

I've flashed custom ROMs in some devices in the past, specially on a Poco F1 and a Mi 11 Ultra (flashed MIUI.EU in it several times). With the OnePlus 9 the process with unlocking the bootloader was a bit different but I got it to work. But when it comes to custom ROMs installation, the end result is always a bricked device and I had to use MSM from OP9 pro to unbrick and then OP9 MSM to get the device back to normal. I've downgraded everytime to OxygenOS 11 but it didn't work. Can someone help me find out what am I doing wrong?
My procedure besides unlocking the bootloader was:

1. Install boot.img
2. From fastboot to recovery
3. Wipe everything (tried not doing it with the same result)
4. Install ROM via ADB (as an update)
5. Wipe everything (tried not doing it with the same result)
6. Reboot
7. Brick..

I've considered it being an ADB drivers problem, but the device is recognized in the computer as an ADB device so I don't think it is.

As I install through ADB, the CMD window keeps the percentage going up but on the device it never shows anything ROM related as it is being installed, just the final message saying steps 2/2 had been completed.

Thanks in advance, and happy flashing guys! :D
 

EtherealRemnant

Senior Member
Sep 15, 2007
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Change to slot A before flashing. Slot B just doesn't flash right most of the time. Sometimes the device still bricks despite doing everything right though and after the last one, I just went back to stock and stayed there. It's far less likely to brick if you're flashing slot A though in my experience.

You are making sure to use the posted recovery image with each ROM as well, right?

Try StagOS as it was the least problematic for me, both flashing and in terms of bugs. Go to slot A like I recommended and then follow the instructions including flashing the copy partitions zip.
 
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Change to slot A before flashing. Slot B just doesn't flash right most of the time. Sometimes the device still bricks despite doing everything right though and after the last one, I just went back to stock and stayed there. It's far less likely to brick if you're flashing slot A though in my experience.

You are making sure to use the posted recovery image with each ROM as well, right?

Try StagOS as it was the least problematic for me, both flashing and in terms of bugs. Go to slot A like I recommended and then follow the instructions including flashing the copy partitions zip.
Hey, I've only tried Nameless OS and EvolutionX.

The think I liked about the Poco F1 is that it had no Slot A/B mess (though I've heard A/B slot is better overall).

I'm pretty sure both recoveries went straight to slot A but I might be wrong.

To be fair, stock OOS12 is working fairly good. I just like to help developing custom ROMs and try new stuff. Next time I find time to mess with the phone I'll try StagOS as you suggested. Thank you for your time and opinion.
 

EtherealRemnant

Senior Member
Sep 15, 2007
3,622
1,095
37
Denver, CO
Hey, I've only tried Nameless OS and EvolutionX.

The think I liked about the Poco F1 is that it had no Slot A/B mess (though I've heard A/B slot is better overall).

I'm pretty sure both recoveries went straight to slot A but I might be wrong.

To be fair, stock OOS12 is working fairly good. I just like to help developing custom ROMs and try new stuff. Next time I find time to mess with the phone I'll try StagOS as you suggested. Thank you for your time and opinion.
If you use the copy partitions zip before you flash and then you reboot recovery, you end up with both partitions having the same data before you flash and much less likelihood of a brick. Also, don't clear data after you flash, that caused me to reboot to fastboot when I was done flashing and at that point I couldn't recover the OS and had to use the MSM.

I am not a fan of the A/B system but I will say that my Pixel 3 XL didn't have this issue.
 
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If you use the copy partitions zip before you flash and then you reboot recovery, you end up with both partitions having the same data before you flash and much less likelihood of a brick. Also, don't clear data after you flash, that caused me to reboot to fastboot when I was done flashing and at that point I couldn't recover the OS and had to use the MSM.

I am not a fan of the A/B system but I will say that my Pixel 3 XL didn't have this issue.
I've never used copy partitions zip in any of my flashing attempts so it might fix my issue. I find it weird that it wasn't mentioned in any of the ROMs I tried but maybe it's something they assume people will do.
 

EtherealRemnant

Senior Member
Sep 15, 2007
3,622
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Denver, CO
I've never used copy partitions zip in any of my flashing attempts so it might fix my issue. I find it weird that it wasn't mentioned in any of the ROMs I tried but maybe it's something they assume people will do.
It's only mentioned in the Stag thread and I think Lineage too but it should work with every ROM since it's only a recovery script that copies the partitions.
 
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mattie_49

Senior Member
Feb 4, 2010
3,293
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Seymour Tn
OnePlus 9 Pro
I've never used copy partitions zip in any of my flashing attempts so it might fix my issue. I find it weird that it wasn't mentioned in any of the ROMs I tried but maybe it's something they assume people will do.
Copy partitions is def what you need. Your using msm then trying to flash. If you took an ota or used copy partitions after msm. You will be all good. Oos has to be on both slots. This is your issue
 
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Copy partitions is def what you need. Your using msm then trying to flash. If you took an ota or used copy partitions after msm. You will be all good. Oos has to be on both slots. This is your issue
so, basically I need to have OOS11 and ensure it is in both slots (by copying the partitions) right? I'm feeling so dumb right now ahah I was going crazy over this
 

mattie_49

Senior Member
Feb 4, 2010
3,293
1,032
Seymour Tn
OnePlus 9 Pro
so, basically I need to have OOS11 and ensure it is in both slots (by copying the partitions) right? I'm feeling so dumb right now ahah I was going crazy over this
It's easier to take an ota update to get oos on both slots truly. Go into system updates. Make sure it's A 11. Seamless updates . However you can do it get it done. Then flashing will be fine.
 
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Can you tell me what is the easiest way to downgrade from A12 to A11 (latest OOS)? The only way I've found was through MSM. It is impossible to install A11 while already being on A12 through OTA right? You're helping me a lot btw, thank you
 

EtherealRemnant

Senior Member
Sep 15, 2007
3,622
1,095
37
Denver, CO
Can you tell me what is the easiest way to downgrade from A12 to A11 (latest OOS)? The only way I've found was through MSM. It is impossible to install A11 while already being on A12 through OTA right? You're helping me a lot btw, thank you
There is a downgrade package posted in the forums here. You install the local upgrade APK and then flash the downgrade package.


The link to the APK is in the post.
 
It's easier to take an ota update to get oos on both slots truly. Go into system updates. Make sure it's A 11. Seamless updates . However you can do it get it done. Then flashing will be fine.

There is a downgrade package posted in the forums here. You install the local upgrade APK and then flash the downgrade package.


The link to the APK is in the post.

Haven't flashed required firmware in both slots.To do this,flashing copy partions before installing custom rom and then reboot phone to recovery to install custom rom.
I'm replying to everyone so that you know that I was successful. It was indeed a partition's problem. Sadly I didn't find the ROM as stable as OOS 12 or OOS 11 so I guess I'll stick with Oneplus software for the time being. Thank you so much for the help :D
 
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EtherealRemnant

Senior Member
Sep 15, 2007
3,622
1,095
37
Denver, CO
I'm replying to everyone so that you know that I was successful. It was indeed a partition's problem. Sadly I didn't find the ROM as stable as OOS 12 or OOS 11 so I guess I'll stick with Oneplus software for the time being. Thank you so much for the help :D
Glad that you got it sorted.

I found the same thing. I'm back on OOS12 C.48 with root. Browsing performance sucks with the CPU throttling they do, and they changed the way they do it so the fixes posted in the 9 Pro forum don't work anymore, but it's otherwise better than all the custom ROMs I tried and I don't have much to complain about.
 

mattie_49

Senior Member
Feb 4, 2010
3,293
1,032
Seymour Tn
OnePlus 9 Pro
Glad that you got it sorted.

I found the same thing. I'm back on OOS12 C.48 with root. Browsing performance sucks with the CPU throttling they do, and they changed the way they do it so the fixes posted in the 9 Pro forum don't work anymore, but it's otherwise better than all the custom ROMs I tried and I don't have much to complain about.
I have to agree with both. I'm also a global unit op9 unlocked on C-48 rooted. Anything that is usually still maintained/updated and not deserted is better than custom. Cherry picking and flashing is overrated. Stock isn't bad at all. You guys enjoy your devices.
 
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    Change to slot A before flashing. Slot B just doesn't flash right most of the time. Sometimes the device still bricks despite doing everything right though and after the last one, I just went back to stock and stayed there. It's far less likely to brick if you're flashing slot A though in my experience.

    You are making sure to use the posted recovery image with each ROM as well, right?

    Try StagOS as it was the least problematic for me, both flashing and in terms of bugs. Go to slot A like I recommended and then follow the instructions including flashing the copy partitions zip.
    1
    Hey, I've only tried Nameless OS and EvolutionX.

    The think I liked about the Poco F1 is that it had no Slot A/B mess (though I've heard A/B slot is better overall).

    I'm pretty sure both recoveries went straight to slot A but I might be wrong.

    To be fair, stock OOS12 is working fairly good. I just like to help developing custom ROMs and try new stuff. Next time I find time to mess with the phone I'll try StagOS as you suggested. Thank you for your time and opinion.
    If you use the copy partitions zip before you flash and then you reboot recovery, you end up with both partitions having the same data before you flash and much less likelihood of a brick. Also, don't clear data after you flash, that caused me to reboot to fastboot when I was done flashing and at that point I couldn't recover the OS and had to use the MSM.

    I am not a fan of the A/B system but I will say that my Pixel 3 XL didn't have this issue.
    1
    I've never used copy partitions zip in any of my flashing attempts so it might fix my issue. I find it weird that it wasn't mentioned in any of the ROMs I tried but maybe it's something they assume people will do.
    It's only mentioned in the Stag thread and I think Lineage too but it should work with every ROM since it's only a recovery script that copies the partitions.
    1
    I've never used copy partitions zip in any of my flashing attempts so it might fix my issue. I find it weird that it wasn't mentioned in any of the ROMs I tried but maybe it's something they assume people will do.
    Copy partitions is def what you need. Your using msm then trying to flash. If you took an ota or used copy partitions after msm. You will be all good. Oos has to be on both slots. This is your issue
    1
    so, basically I need to have OOS11 and ensure it is in both slots (by copying the partitions) right? I'm feeling so dumb right now ahah I was going crazy over this
    It's easier to take an ota update to get oos on both slots truly. Go into system updates. Make sure it's A 11. Seamless updates . However you can do it get it done. Then flashing will be fine.