Database Users

Problem restoring data.img too big

I have an HTC Magic but I can't restore a data.img that it's too big for fastboot:
Code:
sending 'userdata' (160155 KB)... FAILED (remote: data length is too large)
With a smaller one (but 20 days older) it works great (it's about 90MB).
Do you know something about this fastboot limit?
Thank you

Solved by myself using the RA recovery 1.1, with autorestore

Exact same problem
My data.img is 125MB (125503488), and fastboot refuse to flash it to userdata partition
BTW, this is how I reproduce this problem
1) start phone in recovery, and wipe data
2) then flash cyanogen 4.0.4 update.zip thru recovery
3) power down my phone, and take out sdcard (don't want a2sd to run automatic after reboot)
4) power on phone
5) connect phone to computer, and update my a2sd, userinit.sh, and user.conf in phone
6) power down my phone
7) put in sdcard
8) start phone in fastboot, and connect to computer
9) fastboot flash userdata data.img (already grab data.img to the computer ahead of time)
Bamb. Error
What I wanted to do is
a) update to cynanogen 4.0.4 (on 4.0.1 now)
b) keep apps (and existing data) on /data in phone
c) run compcache (thus my modified a2sd)
For those of you who flashes often, how do you accomplish step 2? I probably have 20 - 30 apps, so I suppose I could reinstall them all if push come to shove, but I would avoid it as much as I can
I also want to keep apps on phone, and save sdcard space for something else. I have a feeling a2sd will solve this problem, but I don't want to go down this road.
Does anyone know of a hard limit on how big data.img fastboot can handle?
The odd thing is the recovery restore last backup command work just fine, and can restore my 120+mb data.img just fine. This restore save my bacon more than once!
If this matter, I am running fastboot on a mac
Thanks!

Bump de bump bump
Solution?
q3o84762478648 <requires 10 chars>

Use Titanium backup for the issue with moving the apps from one ROM to another.
Sent from my HTC Magic using XDA App

I have the same problem.
can't flash data.img because it says
sending 'userdata' (395839 KB)...
FAILED (remote: data length is too large)

ROM Upgrade Seems to be Impossible!

Hello!
Yes, I am fairly new to this, but not a noob by any means. I've been upgrading ROM's for a long time, albeit Windows mobile.
I have rooted my Hero - confirmed by installing several ROOT only apps from the market, and accessing commands from su, # prompts.
I can't seem to upgrade my [otherwise stock] Sprint hero despite trying different approaches.
Hugely frustrating, a history of my attempts:
I copied the latest backup recovery file 1.5.2 to the root of my SD card.
I have installed ADB tools
So I open a command prompt and go into Android SDK/tools:
adb shell
su
# flash_image recovery /sdcard/ [recovery file name]
I then type 'reboot recovery' the phone reboots and I have the screen with phone image and large triangle with yellow '!' in it.
I hold 'HOME' and 'END' togerther to access menu of system recovery utility and I can only select 3 options:
reboot system now [Home+back]
apply sdcard:update.zip [Alt+S] * see below)
wipe data/factory rest [Alt+w]
At the bottom of the screen I have the error (which I have investigated and found that no-one seems to be able to explain, yet it doesn't seem to hinder most folks in flashing roms):
E:Can't open /cache/recovery/command
I initially expected to have MORE options as the first thing I wanted to do was create a Nandroid backup, but gave up on trying to do this!
*So I rename the fresh 1.1 rom zip to 'update.zip' and copy to the root of my SD card.
I 'reboot recovery' again, my phone restarts, I choose the 'Apply SDCard:update.zip' option and then it begins to install:
Install from sdcard....
Finding update package....
Opening update package....
Verifying update package....
E:No signature (599 files)
E:Verification failed
Installation aborted
I've tried updating different ROM's with similar negative results - and yes, I have checked the MD5 to ensure ROM's are 'good'
Ideas?
BTW - I still also have the error:
E:Can't open /cache/recovery/command

Get the fresh kitchen and run the auto root feature.

I would agree get the kitchen try the auto root because to me it sounds like there was a problem in your root process. screen that you are getting into is just the fastboot also what I have found to make life easier is rename the RA-Recovery-heroc-1.5.2.img to just recovery.img makes my life a whole lot easier as I mess with my phone so much I have had to RUU several times and that just makes rooting manualy a little faster.

As far as installing the Fresh ROM, I know I had an issue because I was using a MAC and when I downloaded the Zip file, the MAC would unzip it. I finally had to download the Zip file right to my phone and it worked fine.

raylusk said:
As far as installing the Fresh ROM, I know I had an issue because I was using a MAC and when I downloaded the Zip file, the MAC would unzip it. I finally had to download the Zip file right to my phone and it worked fine.
Click to expand...
Click to collapse
That's because you aren't supposed to unzip a rom.

[Q] System image problem

My system partition was erased via fastboot in order to successfully flash a different one, however I'm getting write errors on one I pulled from somebodies' nandroid backup, and a buffer exceeded error when trying to flash the system.img from the leaked stock images thread.
Is there any way to flash the image from my phone (I read that fastboot doesn't handle files over 300mb?) or an alternate image I can use. Everything else is in tact the phone just stalls at the Google screen due to a missing /system

Alex.xTF said:
My system partition was erased via fastboot in order to successfully flash a different one, however I'm getting write errors on one I pulled from somebodies' nandroid backup, and a buffer exceeded error when trying to flash the system.img from the leaked stock images thread.
Is there any way to flash the image from my phone (I read that fastboot doesn't handle files over 300mb?) or an alternate image I can use. Everything else is in tact the phone just stalls at the Google screen due to a missing /system
Click to expand...
Click to collapse
You need a sparse filesystem image. Until the original factory images are made available online (it's in the works, but I don't have an exact date), somebody with a working device could create such an image by running (as root):
# make_ext4fs -l 512m -s /sdcard/system.img /system
This should create a flashable system.img (~145MB) on /sdcard (that you can then grab with adb pull or usb mass storage)

I really appreciate you responding, hopefully I can recover my phone without a return, anybody you can suggest I ask to do this for me?

Anybody with a Nexus S and an adb shell running as root should be able to do this.

Flashing Now Fails

I've been flashing N7 with no issues as recently as over the weekend. Today I tried to flash a new ROM and it failed. Tried a second, different ROM, same result. Do not know what I did. Any thoughts?

Error log would help greatly.

How do I get/generate the log? Haven't had to do it before.
Thanks,
Paul

The logs= errors displayed on the screen provided by the interface you use to flash the rom (recovery, computer...)

Does this help any?
TWRP V2.4.4.0
Updating partition details
E: Unable to open zip file
Error flashing zop
Updating partition details...

do I need to create a partition? Never get more details despite the tease.
Thanks,

First -
Try and download a different (NEWER) TWRP. Re-flash TWRP. Try again
or
Have you tried completely wiping the device? And pushing a ROM from ADB or using a USB OTG and Memory stick?
I had issues with my nexus becoming VERY unstable. Leading to issues.
I completely, and I mean completely, wiped. To the point that all that device basically had was a recovery, and a bootloader.
I proceeded to flash again, BOOM all fixed up.

Is there a new TWRP?
I did a factory restore after wiping everything thing, if that is what you mean?
It was working as expected last week, don't know what I did to screw it up

Boot recovery try the operation, choose advanced then copy log to sdcard. The paste the log results.
sent via electromagnetic radiation.

ibsk8 said:
Boot recovery try the operation, choose advanced then copy log to sdcard. The paste the log results.
sent via electromagnetic radiation.
Click to expand...
Click to collapse
Did this, and it said it copied but I am unable to locate it. It says 0\media\data But that folder structure doesn't exist, at least according to file expert

Will a complete wipe/restore create a partition?

pmgreen said:
Will a complete wipe/restore create a partition?
Click to expand...
Click to collapse
None of the instructions currently found in this forum alters the partitioning of the N7. Not fastboot & not the custom recovery, either.
You are chasing a red herring I think. That message you see is about the recovery performing a scan to check to see if there is a change in file systems (or partitioning of external devices) ... which might have occurred in preceding (custom recovery) operations, but didn't in this particular case.
pmgreen said:
Does this help any?
TWRP V2.4.4.0
Updating partition details
E: Unable to open zip file
Error flashing zop
Updating partition details...
Click to expand...
Click to collapse
Focus your efforts here; it certainly looks like a first-order problem.

bftb0 said:
None of the instructions currently found in this forum alters the partitioning of the N7. Not fastboot & not the custom recovery, either.
You are chasing a red herring I think. That message you see is about the recovery performing a scan to check to see if there is a change in file systems (or partitioning of external devices) ... which might have occurred in preceding (custom recovery) operations, but didn't in this particular case.
Focus your efforts here; it certainly looks like a first-order problem.
Click to expand...
Click to collapse
Think reinstalling TWRP would help? It was working fine so I'm a bit stumped what changed and why

pmgreen said:
Think reinstalling TWRP would help? It was working fine so I'm a bit stumped what changed and why
Click to expand...
Click to collapse
You can also soft-boot a recovery without actually flashing it, e.g.
Code:
fastboot boot custom-recovery.img
I suppose you could then poke around and see if it is having troubles mounting any of the normal partitions (/data, /system, or /cache). Look in the kernel boot log of the recovery (cat /proc/kmsg or "dmesg") to see if anything looks strange, etc.
There have been a couple of reports from folks who developed problems that looked like eMMC flash media errors - loss of partitions, failure to mount /data, et cetera. At the moment though, your symptoms are very generic and non-specific, as in "it doesn't boot".
I suppose you saw no errors at all reported on the screen during that stock-install-via-fastboot procedure?

bftb0 said:
You can also soft-boot a recovery without actually flashing it, e.g.
Code:
fastboot boot custom-recovery.img
I suppose you could then poke around and see if it is having troubles mounting any of the normal partitions (/data, /system, or /cache). Look in the kernel boot log of the recovery (cat /proc/kmsg or "dmesg") to see if anything looks strange, etc.
There have been a couple of reports from folks who developed problems that looked like eMMC flash media errors - loss of partitions, failure to mount /data, et cetera. At the moment though, your symptoms are very generic and non-specific, as in "it doesn't boot".
I suppose you saw no errors at all reported on the screen during that stock-install-via-fastboot procedure?
Click to expand...
Click to collapse
The only error is that it can't open the zip. I've tried downgraded TWRP, then upgrading back. Tried flashing the existing rom.
Nothing has worked. The N7 is functional, just will not allow me to flash

pmgreen said:
The only error is that it can't open the zip. I've tried downgraded TWRP, then upgrading back. Tried flashing the existing rom.
Nothing has worked. The N7 is functional, just will not allow me to flash
Click to expand...
Click to collapse
Well, if the source material can't be opened, then there is nothing to be flashed.
So maybe it is better to call this a "can't open files" problem instead of a "can't flash" problem.
Are there any special characters in the file name ... or spaces? If so, try renaming the file so the name only contains [a-z], [A-Z], [0-9] plus dash, underscore, and dot.
The other thing that can happen is if you drop a file in /data/media/0 as the root user, it will show up under /sdcard, but can't be read by non-privileged users via the /sdcard/ path. I'm not sure what the exact details are here - much less why this would effect the recovery (as you would expect everything to be running as root there) - but you can detect this problem by using a terminal emulator, and looking for differences in ownership or file permission:
Code:
$ su
# cd /data/media/0
# ls -ld *
use chown and chmod as appropriate to fix files as needed

bftb0 said:
Well, if the source material can't be opened, then there is nothing to be flashed.
So maybe it is better to call this a "can't open files" problem instead of a "can't flash" problem.
Are there any special characters in the file name ... or spaces? If so, try renaming the file so the name only contains [a-z], [A-Z], [0-9] plus dash, underscore, and dot.
The other thing that can happen is if you drop a file in /data/media/0 as the root user, it will show up under /sdcard, but can't be read by non-privileged users via the /sdcard/ path. I'm not sure what the exact details are here - much less why this would effect the recovery (as you would expect everything to be running as root there) - but you can detect this problem by using a terminal emulator, and looking for differences in ownership or file permission:
Code:
$ such
# cd /data/media/0
# ls -ld *
use chown and chmod as appropriate to fix files as needed
Click to expand...
Click to collapse
Thanks bftb, you are correct it's a can't open zip. No error than fail and it can't open the zip. It says updating partition but nothing changes
The file names are from the developers, once of which I recently successfully flashed. Tried coping the log to the SD card, but unable to find /data/media/0. Do I need to recreate a partition?

(FYI there was an auto-correct typo in my prior post - "su" not "such". Derp)
pmgreen said:
Do I need to recreate a partition?
Click to expand...
Click to collapse
No. (There is no way to do that with the tools we have anyway)
Unless what you mean by "recreate" is rebuild/reinitialize a filesystem in a partition - that's a possibility.
You need to try and figure out why you can't read files.
As a workaround, you can put files on a USB key (FAT formatted, not NTFS) and using TWRP access them by putting the USB key on the other end of a OTG cable.
Your posts are a bit vague - I can't even tell if you have tried other ROM files, whether you checked them to see if they are the correct size/checksum, etc.

pmgreen said:
Tried coping the log to the SD card, but ...
Click to expand...
Click to collapse
At this point, your best approach is still to follow the initial advice of 'ibsk8'. Look in the log file for any further details about errors that occurred.
The logs are typically in /cache/recovery/ or (while the custom recovery is running) in /tmp
Use "adb pull" to get the log file to your PC and have a look at it. If you can't find anything obvious in there, then cut-n-paste the file to http://pastebin.com and provide the link to us.

bftb0 said:
At this point, your best approach is still to follow the initial advice of 'ibsk8'. Look in the log file for any further details about errors that occurred.
The logs are typically in /cache/recovery/ or (while the custom recovery is running) in /tmp
Use "adb pull" to get the log file to your PC and have a look at it. If you can't find anything obvious in there, then cut-n-paste the file to http://pastebin.com and provide the link to us.
Click to expand...
Click to collapse
I am not familiar using ADB pull. Tried using a root file manager to access the log but don't see.
Greatly appreciate your help, let me know what other info I should paste.
Thanks,

createTarFork() process ended with ERROR: 255 on backup

Hiya XDA, So i'm trying to back up my phone (Running CM13) to my memory stick, and it worked before, but now it seems to have broken and I don't know what the issue is. My log (adb pull /tmp/recovery.log) is below
Heres what I've tried
Reflashing TWRP
Going to a slightly older version (3.0.2-1)
Enabling and disabling encryption
with and without compression
Skipping MD5 and leaving it on
[BACKUP STARTED]
* Backup Folder: /usb-otg/TWRP/BACKUPS/ENU7N15A10005575/2016-12-10--16-58-06_cm_angler-userdebug_6.0.1_MOB30Z_b4fbca03c0/
Backing up Boot...
I:Reading '/dev/block/mmcblk0p34', writing '/usb-otg/TWRP/BACKUPS/ENU7N15A10005575/2016-12-10--16-58-06_cm_angler-userdebug_6.0.1_MOB30Z_b4fbca03c0/boot.emmc.win'
Iartition Backup time: 4
Backing up System...
Error opening: '/system/addon.d' (Not a directory)
I:Error in Generate_TarList!
Error creating backup.
I:InfoManager saving '/usb-otg/TWRP/BACKUPS/ENU7N15A10005575/2016-12-10--16-58-06_cm_angler-userdebug_6.0.1_MOB30Z_b4fbca03c0/system.info'
createTarFork() process ended with ERROR: 255
Backup Failed. Cleaning Backup Folder.
I:Copying file /tmp/recovery.log to /usb-otg/TWRP/BACKUPS/ENU7N15A10005575/recovery.log
I:Set page: 'action_complete'
Iperation_end - status=1
E:error opening '/usb-otg/LOST.DIR' -- error: No such file or directory
E:error opening '/usb-otg/TWRP' -- error: No such file or directory

Looks as though your memory stick isn't formatted correctly. Try Fat32 or possibly EXT4

It is Fat32?
frap129 said:
Looks as though your memory stick isn't formatted correctly. Try Fat32 or possibly EXT4
Click to expand...
Click to collapse
I don't have access to a Linux machine, but I could format it in my phone?
I'll try that. and will post any updates.
UPDATE:
Formatted it in Android, still same error
UPDATE 2:
Tried a different USB stick, same error.
The USB sticks I am using are:
amazon.com/SanDisk-Cruzer-Orbit-Drive-SDCZ58-032G-B35/dp/B00BPHTH4C
and
amazon.com/SanDisk-Ultra-Flair-Performance-SDCZ73-064G-G46/dp/B015CH1NAQ/

Remove /system/addon-d in twrp ?

Will my phone work properly after doing that?
UPDATE:
Renamed it to addon-dee in my prefered Filemanager (ES) and it's backing up now.
(thank god I decided to use a USB3 stick this time)
UPDATE 2:
Phone backed up and now is working fine! thanks.

I was having the same error until I updated TWRP to the unofficial 3.0.2-3

I have this problem and l have 17g free space in my internal storage but receive error 255 and i don't find addon in my storage plz help me for fixing this error
Sent from my Le X820 using XDA-Developers mobile app

m890 said:
I have this problem and l have 17g free space in my internal storage but receive error 255 and i don't find addon in my storage plz help me for fixing this error
Sent from my Le X820 using XDA-Developers mobile app
Click to expand...
Click to collapse
Should be under /system/ . Are you rooted? I don't know if you can see that part of system if you're not rooted.

My device is rooted but this file isn't there.
Sent from my Le X820 using Tapatalk

m890 said:
I have this problem and l have 17g free space in my internal storage but receive error 255 and i don't find addon in my storage plz help me for fixing this error
Sent from my Le X820 using XDA-Developers mobile app
Click to expand...
Click to collapse
It's not always the same file. Look at your log to see which file/dir is problematic.

SOLVED createTarFork() process ended with ERROR=255
SOLUTION
This solution worked on my Zenfone 3, running lineage Android 7.1.2.
I tried many other things, like flashing different versions of TWRP, deleting the recovery directory, renaming files and all the like.
You may deselect compression, change the TWRP-date / time : nothing works !
You need an PC / Notebook with adb installed.
- start your phone in recovery-mode (TWRP)
- connect to PC and get the recovery.log with following adb command
adb pull /tmp/recovery.log
You will find a copy of the file recovery.log in the directory, from which you started the command
- open an editor or choose your favourite file viewer to open recover.log
- search for the last entry of the word "Error"
- in the line before that, the recovery.log states the name of the file that causes the problem
(in my case it was /system/addon.d)
- disconnect phone from PC.
- restart your phone in "normal" restart (do NOT boot to recovery mode)
- use a root file browser (I used ES-explorer with root enabled) and navigate to that directory/file
- delete the file (which I did not do - I tried some other steps)
- restart phone
This took 3-4 minutes, but I did not delete the file addon.d right away. Instead, I did this:
step 1
navigated to /system/addon.d and copied addon.d to SD-card
step 2
in /system/ , I renamed addon.d "addon_BU.d".
This was successful. In /system/ , the only file visible was now "addon_BU.d"
step 3
tried to create a directory named addon.d inside /system/ because my recovery.log said quote\ ... system/addon.d (not a directory) ... \unquote
FAILED. The directory could not be created by ES-explorer
step 4
copied my backup file addon.d from SD-card back into its original location /system/.
This, I though, would work just fine, because I had renamed the original addon.d to addon_BU.d.
So after restoring addon.d , the only thing left to do would be delte addon_BU.d.
ES-explorer reported no error, but - surprise - there was no file "addon.d" present in /system/
The only file still there was "addon_BU.d"
well, let's go to
step 5
rename addon_BU.d back to it's original name "addon.d" using ES-explorer
FAILED.
addon_BU.d could not be renamed - this file really was screwed up big time !!!
I ended up with no addon.d - so I could have deleted it right away istead of starting my trial with step 1 ...
step 6
Anyway. Shut dowm my phone.
Rebooted my phone normally (not to recovery mode !!!)
This took considerably longer than normal - my heart rate had began to increase slightly if not to say I began to feel like a squirrel on red bull...
After roughly 3 minutes, I had a successful reboot to my OS (lineage Android 7.1.2)
step 7
Reboot again, this time to recovery mode (=TWRP)
and: backups work again.
Don't ask me why this worked and if it will work for you, but hey, give it a triy and let me know...
TheLMGN said:
Hiya XDA, So i'm trying to back up my phone (Running CM13) to my memory stick, and it worked before, but now it seems to have broken and I don't know what the issue is. My log (adb pull /tmp/recovery.log) is below
Heres what I've tried
Reflashing TWRP
Going to a slightly older version (3.0.2-1)
Enabling and disabling encryption
with and without compression
Skipping MD5 and leaving it on
[BACKUP STARTED]
* Backup Folder: /usb-otg/TWRP/BACKUPS/ENU7N15A10005575/2016-12-10--16-58-06_cm_angler-userdebug_6.0.1_MOB30Z_b4fbca03c0/
Backing up Boot...
I:Reading '/dev/block/mmcblk0p34', writing '/usb-otg/TWRP/BACKUPS/ENU7N15A10005575/2016-12-10--16-58-06_cm_angler-userdebug_6.0.1_MOB30Z_b4fbca03c0/boot.emmc.win'
Iartition Backup time: 4
Backing up System...
Error opening: '/system/addon.d' (Not a directory)
I:Error in Generate_TarList!
Error creating backup.
I:InfoManager saving '/usb-otg/TWRP/BACKUPS/ENU7N15A10005575/2016-12-10--16-58-06_cm_angler-userdebug_6.0.1_MOB30Z_b4fbca03c0/system.info'
createTarFork() process ended with ERROR: 255
Backup Failed. Cleaning Backup Folder.
I:Copying file /tmp/recovery.log to /usb-otg/TWRP/BACKUPS/ENU7N15A10005575/recovery.log
I:Set page: 'action_complete'
Iperation_end - status=1
E:error opening '/usb-otg/LOST.DIR' -- error: No such file or directory
E:error opening '/usb-otg/TWRP' -- error: No such file or directory
Click to expand...
Click to collapse

1gnc said:
SOLUTION
This solution worked on my Zenfone 3, running lineage Android 7.1.2.
I tried many other things, like flashing different versions of TWRP, deleting the recovery directory, renaming files and all the like.
You may deselect compression, change the TWRP-date / time : nothing works !
You need an PC / Notebook with adb installed.
- start your phone in recovery-mode (TWRP)
- connect to PC and get the recovery.log with following adb command
adb pull /tmp/recovery.log
You will find a copy of the file recovery.log in the directory, from which you started the command
- open an editor or choose your favourite file viewer to open recover.log
- search for the last entry of the word "Error"
- in the line before that, the recovery.log states the name of the file that causes the problem
(in my case it was /system/addon.d)
- disconnect phone from PC.
- restart your phone in "normal" restart (do NOT boot to recovery mode)
- use a root file browser (I used ES-explorer with root enabled) and navigate to that directory/file
- delete the file (which I did not do - I tried some other steps)
- restart phone
This took 3-4 minutes, but I did not delete the file addon.d right away. Instead, I did this:
step 1
navigated to /system/addon.d and copied addon.d to SD-card
step 2
in /system/ , I renamed addon.d "addon_BU.d".
This was successful. In /system/ , the only file visible was now "addon_BU.d"
step 3
tried to create a directory named addon.d inside /system/ because my recovery.log said quote\ ... system/addon.d (not a directory) ... \unquote
FAILED. The directory could not be created by ES-explorer
step 4
copied my backup file addon.d from SD-card back into its original location /system/.
This, I though, would work just fine, because I had renamed the original addon.d to addon_BU.d.
So after restoring addon.d , the only thing left to do would be delte addon_BU.d.
ES-explorer reported no error, but - surprise - there was no file "addon.d" present in /system/
The only file still there was "addon_BU.d"
well, let's go to
step 5
rename addon_BU.d back to it's original name "addon.d" using ES-explorer
FAILED.
addon_BU.d could not be renamed - this file really was screwed up big time !!!
I ended up with no addon.d - so I could have deleted it right away istead of starting my trial with step 1 ...
step 6
Anyway. Shut dowm my phone.
Rebooted my phone normally (not to recovery mode !!!)
This took considerably longer than normal - my heart rate had began to increase slightly if not to say I began to feel like a squirrel on red bull...
After roughly 3 minutes, I had a successful reboot to my OS (lineage Android 7.1.2)
step 7
Reboot again, this time to recovery mode (=TWRP)
and: backups work again.
Don't ask me why this worked and if it will work for you, but hey, give it a triy and let me know...
Click to expand...
Click to collapse
Hi, thank you for a fix but this is an 10 month old thread. The issue was with TWRP 3.0.2-2. Along with an EFS issue that plagued TWRP 3.0.1-2, both issues have long since been resolved.
Sent from my Nexus 5X using Tapatalk

simple and working solution :
by @yannick818
"looks like it's an error with parallel apps oder multiple users. since i do not use something like that, i just removed this user with the android terminal emulator:
su
pm remove-user 999
everything was fine after that"

I could resolve my nandroid /data backup error on my EMUI 8.0 Mediapad M5 device with those following steps:
1 - Use a correct TWRP implementation
TWRP need to access the uncyphered partition /data.
There no possibility to backup it, if TWRP does not implement deciphering user data partition.
2 - Remove all users except user 0 (the administrator)
You can verify that there is no unwanted users, looking at directory /data/user : the only subdirectory should be "0".
To remove the others users :
Remove the PrivateSpace if you have one (Settings > Security & Privacy > PrivateSpace, and tap on the garbage can).
Remove all the secondary users (Settings > Users & accounts > users, and tap on each users to delete them). Keep just the main administrator user.
On EMUI, remove all twins applications (Settings > Apps & Notifications > App Twin, and disable all twin apps).
On OxygenOS, remove all parallel apps (Settings > Apps > Parallel Apps, and disable all parallel apps).
On MIUI, remove all dual apps (Settings > Dual Apps, and disable all dual apps)
On others devices ... you must find all parameters that create those unwanted users.
If you are not able to get the correct settings to suppress those users, in last resort you can try this command : "pm remove-user user-no. (For example "pm remove-user 999").
3 - Do not forget to protect your backups by a password
This would be stupid to cipher your /data partition and keep backups of this partition unprotected.
These steps fixed the nandroid backup problem for /data partition on my Huawei Mediapad M5 device.
I post on this forum because I hope that this will be helpful for others devices owners.