I have sony xperia P device and I want to flash its ROM to get Marshmallow(I currently have android 4.0.4).
I want to do full backup of my phone before doing this, I knew about adb backup
command, I installed android-tools from my Arch linux repos and issued :
adb backup -all -apk -shared -f momsmobile.ab
it shows : Now unlock your device and confirm the backup operation.
but Nothing shows at all, I have USB debugging enabled and tried to put a password the Developer option "Desktop password for backup".
I also tried following Arch wiki and added udev rules, this is the rule file :
SUBSYSTEM=="usb", ATTR{idVendor}=="xxxx", MODE="0666", GROUP="adbusers"
SUBSYSTEM=="usb",ATTR{idVendor}=="xxxx",ATTR{idProduct}=="yyyy",SYMLINK+="android_adb"
SUBSYSTEM=="usb",ATTR{idVendor}=="xxxx",ATTR{idProduct}=="yyyy",SYMLINK+="android_fastboot"
I'm sure the vendor's and product's id are correct(the real ones aren't provided for privacy).
the above didn't work too, I still get no confirm prompt, although when I issue adb devices
I can see mine there.
Basically I have the same issue as this question, only this question has different device model(Sumsung vs Sony) and it's not answered.
Lastly I tried to disable all my antivirus protections, I'm using avast mobile security and disabled every thing but still didn't work.
So what's the problem ?
PS
I don't want to root the device(at least not on backup phase) and I don't want to use any apps.