The S3 was a great flagship device which is still owned by a lot of people even today. That being said, the device was far from perfect as it did have its fair share of problems. One of those problems is the infamous, “Unable to mount EFS partition” error that causes the phone to brick itself even though you had done nothing wrong. This error can only be seen by booting into the stock recovery which is why a lot of people quite often don’t even bother with it but if you have a S3 that doesn’t boot up even after flashing the stock firmware, then perhaps this guide can help you fix it.
Disclaimer: We take no responsibility for any damages done to your device either during or after the procedure; please proceed at your own risk.
Prerequisites: You will require
- ADB & Fastboot set up on your computer along with your device’s USB Drivers
- Odin 3.07 or higher.
- Flash the stock firmware (just for safety) by following our guide here
- Make your device boot into download mode again as it won’t boot up and flash the TWRP recovery image to your phone by first downloading it from here. I recommend using 126.96.36.199 as other versions quite often don’t recognize the phone in the recovery.
- Reboot directly into recovery by holding Power+Home+Vol. UP as soon as the flash finishes. Let go once you see the S3 screen.
- Once in TWRP, in the CMD window opened in the ADB folder, type these commands: “adb shell” then type: “mke2fs /dev/block/mmcblk0p3” and finally: “mount -w -t ext4 /dev/block/mmcblk0p3”
- Once done, reboot the phone. It should boot back to the home screen but you will see a yellow text box on the home screen.
- To get rid of that, root your phone using one of our many guides and install Astro File Explorer
- Tap Tools in Astro, go down and turn on Root Explorer.
- Go to EFS Folder on your phone via the explorer, open Factory folder and then edit the Factorymode file by using Astro Text Editor.
- Change the value of the file from OFF to ON. Save it
- Reboot your phone and that’s it, the error should be fixed now.