[Device Reviews and Information] matiptp:
Santosst thanks for your reply.

I try to install Android 9 following Your instructions. I managed to fulfill first 19 steps (twrp works fine, fastboot flash system system-arm64-aonly-vanilla-nosu.img), but when I try to install magisk 20.4 or 21.0 from .zip (via twrp) I get the error:

<- Nothing to be fixed here, the boot image you gave is not standard AOSP boot image

My recovery.log:

***********************
Magisk 20.4 Installer
***********************
- Mounting /system
- Mounting /vendor
- Target image: /dev/block/mmcblk0p22
- Device platform: arm64
- Removing system installed root
- Constructing environment
java.lang.IllegalArgumentException: Invalid image header: missing magic
at a.v3.b(Unknown Source:176)
at a.v3.a(Unknown Source:20)
at a.a.main(:1)
- Unpacking boot image
Parsing boot image: [/dev/block/mmcblk0p22]
! Unsupported/Unknown image format
- Unmounting partitions
Updater process ended with ERROR: 1
I:Install took 4 second(s).
Error installing zip file '/external_sd/DCIM/Magisk-v20.4_2.zip'
Updating partition details...
I:Data backup size is 4MB, free: 54651MB.
I:Unable to mount '/usb-otg'
I:Actual block device: '', current file system: 'auto'
...done
I:Set page: 'flash_done'
I:operation_end - status=1
I:Set page: 'clear_vars'
I:Set page: 'install'
I:Set page: 'flash_confirm'
I:Set page: 'flash_zip'
I:operation_start: 'Flashing'
Installing zip file '/external_sd/DCIM/Magisk-v20.4-uninstaller-20200323.zip'
Checking for Digest file...
Skipping Digest check: no Digest file found
I:Update binary zip
Verifying package compatibility...
Package doesn't contain compatibility.zip entry
I:Zip does not contain SELinux file_contexts file in its root.
I:Legacy property environment not used in updater.
2034+0 records in
2034+0 records out
2082816 bytes (1.9 M) copied, 0.008881 s, 224 M/s
1410+1 records in
1410+1 records out
1443916 bytes (1.3 M) copied, 0.005956 s, 231 M/s
Archive: /external_sd/DCIM/Magisk-v20.4-uninstaller-20200323.zip
inflating: META-INF/com/google/android/update-binary
inflating: META-INF/com/google/android/updater-script
inflating: arm/magiskboot
inflating: chromeos/futility
inflating: chromeos/kernel.keyblock
inflating: chromeos/kernel_data_key.vbprivk
inflating: util_functions.sh
inflating: x86/magiskboot
inflating: META-INF/MANIFEST.MF
inflating: META-INF/CERT.SF
inflating: META-INF/CERT.RSA
********************
Magisk Uninstaller
********************
- Mounting /system
- Mounting /vendor
- Mounting /persist
mount: can't find /persist in /etc/fstab
- Device platform: arm64
! Cannot access /data, please uninstall with Magisk Manager
- Unmounting partitions
Updater process ended with ERROR: 1
I:Install took 1 second(s).
Error installing zip file '/external_sd/DCIM/Magisk-v20.4-uninstaller-20200323.zip'
Updating partition details...
I:Data backup size is 4MB, free: 54651MB.
I:Unable to mount '/usb-otg'
I:Actual block device: '', current file system: 'auto'
...done
I:Set page: 'flash_done'
I:operation_end - status=1
I:Set page: 'clear_vars'
I:Set page: 'install'
I:Set page: 'flash_confirm'
I:Set page: 'flash_zip'
I:operation_start: 'Flashing'
Installing zip file '/external_sd/DCIM/Magisk-v21.0.zip'
Checking for Digest file...
Skipping Digest check: no Digest file found
I:Update binary zip
Verifying package compatibility...
Package doesn't contain compatibility.zip entry
I:Zip does not contain SELinux file_contexts file in its root.
I:Legacy property environment not used in updater.
2026+0 records in
2026+0 records out
2074624 bytes (1.9 M) copied, 0.008237 s, 240 M/s
1381+1 records in
1381+1 records out
1415016 bytes (1.3 M) copied, 0.006169 s, 219 M/s
Archive: /external_sd/DCIM/Magisk-v21.0.zip
inflating: META-INF/com/google/android/update-binary
inflating: META-INF/com/google/android/updater-script
inflating: arm/magiskboot
inflating: arm/magiskinit
inflating: arm/magiskinit64
inflating: chromeos/futility
inflating: chromeos/kernel.keyblock
inflating: chromeos/kernel_data_key.vbprivk
inflating: common/addon.d.sh
inflating: common/boot_patch.sh
inflating: common/magisk.apk
inflating: common/util_functions.sh
inflating: x86/magiskboot
inflating: x86/magiskinit
inflating: x86/magiskinit64
inflating: META-INF/MANIFEST.MF
inflating: META-INF/CERT.SF
inflating: META-INF/CERT.RSA
***********************
Magisk 21.0 Installer
***********************
- Mounting /system
- Mounting /vendor
- Target image: /dev/block/mmcblk0p22
- Device platform: arm64
- Constructing environment
java.lang.IllegalArgumentException: Invalid image header: missing magic
at jh1.b(Unknown Source:176)
at jh1.c(Unknown Source:19)
at a.a.main(:1)
- Unpacking boot image
Parsing boot image: [/dev/block/mmcblk0p22]
! Unsupported/Unknown image format
- Unmounting partitions
Updater process ended with ERROR: 1
I:Install took 4 second(s).
Error installing zip file '/external_sd/DCIM/Magisk-v21.0.zip'
Updating partition details...
I:Data backup size is 5MB, free: 54650MB.
I:Unable to mount '/usb-otg'
I:Actual block device: '', current file system: 'auto'
...done
I:Set page: 'flash_done'
I:operation_end - status=1
E:recv error on uevent
I:Set page: 'clear_vars'
I:Set page: 'install'
I:Set page: 'main'
I:Set page: 'clear_vars'
I:Set page: 'main2'
I:Set page: 'advanced'
I:Set page: 'copylog'
Truncating string cache entries.
I:Set page: 'action_page'
I:operation_start: 'Copy Log'
I:Copying file /tmp/recovery.log to /data/media/recovery.log

help needed :crying: