TWRP error (operation not permited) when backup - Android Q&A, Help & Troubleshooting

Hello,
I need help for TWRP on my Samsung Galaxy A20e. My device is rooted for a while and TWRP is newly installed. But the problem is when I try to backup something, I got an error while creating the folder TWRP with the mension of operation not permited. I also have a problem when I touch the Install button, I see a list of folders with random generated names like in the photo. Can anybody help me to solve this problem? I can give more informations if needed.
Thanks for helping !
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your device is encrypted. you must disable encryption and factory reset device in order to become TWRP functional, as TWRP cannot handle samsung encryption. or use other backup method such as Migrate.

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Ok I tried what you wrote but it works only while I don't boot my device after factory reset it. If it happens, the encryption enables automatically and I can't backup anymore. Do you have a solution for this ?

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you must disable encryption in /vendor/etc/fstab.samsungexynos7884
(can maybe done with zip)
https://forum.xda-developers.com/t/recovery-unofficial-twrp-3-4-0-0-for-galaxy-a20e-a202f.4141767

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How am I supposed to do that ? I tried everything with this file. There is a mount option for /data "filencryption=ice". I tried to delete this with a file editor in the stock system but when I reboot my phone it reappears. When I this this in TWRP the system can't boot.
https://forum.xda-developers.com/t/recovery-unofficial-twrp-3-4-0-0-for-galaxy-a20e-a202f.4141767
Click to expand...
Click to collapse
This link cannot help me because it is just a tutorial and when I do exactly like in i get the same results. I don't unerstand why my phone has this problem and not others. If you have other ideas i would be good

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there is download for Disable_Dm-Verity_ForceEncrypt_03.04.2020.zip flashable zip which is supposed to patch fstab (last step in tutorial). you must mount system/vendor writeable (checkbox in TWRP)

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aIecxs said:
there is download for Disable_Dm-Verity_ForceEncrypt_03.04.2020.zip flashable zip which is supposed to patch fstab (last step in tutorial). you must mount system/vendor writeable (checkbox in TWRP)
Click to expand...
Click to collapse
I tried installing this zip file from the SD card but it didn't boot (locked on samsung logo) so I did a factory reset with TWRP and after configuring, I got the same results than before.

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- in TWRP double check your vendor partition is separate partition (or directory inside system partition)
- in TWRP terminal make sure partition is mounted rw
Code:
mount /system w
mount /vendor w
mount
- install Disable_Dm-Verity_ForceEncrypt_03.04.2020.zip
- in TWRP terminal double check fstab.samsungexynos7884 file fileencryption= flag is gone
Code:
cat /vendor/etc/fstab.*
- in TWRP - wipe - format data - type yes

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Thanks for the instructions. It works perfectly ! I am just an idiot because I didn't wipe /data in TWRP but I just swiped to factory reset. Thank you a lot !

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maybe I was misleading you with factory reset. might be that TWRP factory reset just behaves like simple wipe, where only files are deleted excluding /data/media
formatting whole partition is required for removing encryption.
edit: Please note if you're interested in undo the patch, you must restore vendor partition. you can of course add the fileencryption= flag back with text editor yourself. However that requires linux line endings (LF) so you can't use Windows text editor (CRLF) that's why you should use Notepad++ and enable view for invisible chars with (π) button. Do not simply copy file back into /vendor you will lose file permissions. Do not use sed you still would lose secontext. only copy content of file into old existing file like this.
Code:
cat /tmp/fstab.new > /vendor/etc/fstab.samsungexynos7884
Btw if you're running custom ROM (such as LineageOS) it's possible to break samsung encryption and use AOSP encryption as fallback by deleting keystore.mdfpp.so and keystore.msm8953.so from /vendor/lib/hw. This way you can use TWRP on encrypted device.