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How to fix - E:failed to mount /efs (Invalid argument)

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Thanks Meter 387
Posts: 520
Join Date: Feb 2011
Location: Monaghan

Phone How to fix - E:failed to mount /efs (Invalid argument)

My phone was dead due to unknown reason. It was very slow for last couple of days, so I reboot the phone into recovery and then wipe cache and dalvik. After the wipe I reboot the phone but it stuck on Samsung logo. So I tried different unsuccessful methods like, flash stock ROM, restore efs folder, etc...

After flashing the stock ROM, rebooted the phone into recovery for factory reset, then only I noticed the error E:failed to mount /efs (Invalid argument). If you are on CWM recovery then you may not see this error.

Flash an official firmware from sammobile
Flash CWM recovery
Boot into Recovery
Select mount and storage -> mont /system
Connect your phone to PC using USB cable
Open ADB command window and type the following commands
adb shell
mke2fs /dev/block/mmcblk0p3
mount -w -t ext4 /dev/block/mmcblk0p3
Now your phone will boot, but it may be in factory mode (ie you can see yellow box showing some ROM information).

Remove factory mode:
There are different methods that we can use to remove factory mode
In my case
1. Installed custom ROM to get root access
2. Instaled kTool
3. Copy the backup of my efs into sdcard (you can use .img or tar file)
4. Open kTool and restore the efs
5. Reboot the phone

* This method is the easiest and safest method because when you are getting the efs mount error there is a chance of loosing your IMEI and some other files, in that situation the following methods will not work.


1. Root your phone (Either root manually or install a custom ROM)
2. Install ES File Explorer
3. Open ES File Explorer and turn on Root Explorer
4. Navigate to /efs folder
5. Open factorymode as txt in ES Note Editor
6. Change it from OFF to ON and save
7. Reboot your phone


1. Root your phone (Either root manually or install a custom ROM)
2. Install Terminal Emulator
3. Run the following commands
rm /efs/FactoryApp/keystr
rm /efs/FactoryApp/factorymode
echo -n ON >> /efs/FactoryApp/keystr
echo -n ON >> /efs/FactoryApp/factorymode
chown 1000.1000 /efs/FactoryApp/keystr
chown 1000.1000 /efs/FactoryApp/factorymode
chmod 0744 /efs/FactoryApp/keystr
chmod 0744 /efs/FactoryApp/factorymode

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Thanks Meter 22
Posts: 57
Join Date: Feb 2013
I can't find factorymode in efs folder.

Sent from my GT-I9300
Thanks Meter 5
Posts: 60
Join Date: Aug 2014
Restoring this kind of backup will also remove factory mode (at least it did when I softbricked my i9305 and had to recover efs).
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