Unlocking the bootloader allows you to put custom ROMs, kernels and boot images on your Xperia Z Ultra which cannot be done otherwise. Say you want to install an AOSP based ROM on your Xperia Z Ultra which need to change the boot image on the device to be compatible with the AOSP code then it can only be done by unlocking the bootloader on your device.
Generally, rooting and custom recovery installation also requires an unlocked bootloader, but thanks to the developer community at work for Xperia devices that root is often achieved even without unlocking the bootloader.
Also thanks to Sony for having their entire range of Xperia devices released since 2011 to be bootloader unlockable. Not every Android manufacturer does that, at-least not so easy.
The bootloader unlocking process on Xperia Z Ultra is fairly simple. And with our step by step instructions with screenshots below, even noob users will be able to do it easily.
Two methods of unlocking the Bootloader on Xperia Z Ultra
There are two methods you could choose from to unlock the bootloader on your Sony Xperia Z Ultra
Unofficially using Flashtool: You can unlock the bootloader on your device using a program called Flashtool. Getting the bootloader unlocked through flashtool is very quick compared to Sony’s official way of doing it. And on a plus note you also save yourself from letting Sony know that you tried to unlock your device’s bootloader (which voids warranty)
Officially from Sony’s website: You can follow Sony’s official way of unlocking the bootloader which is also simple and easy to follow, but not as friendly as Flashtool. In the official method you’ve to get the bootloader unlock key from Sony’s website, which lets the manufacturer know that you intended to unlock your device’s bootloader (which voids warranty) by provding them your phone’s IMEI number to get the key.
Below are full step by step installation instructions for both the methods discussed above. So proceed with whatever method you think is best. In our opinion, go with the Flashtool method. It’s much easier to unlock bootloader using Flashtool.
You’ll void the warranty of your Sony Xperia Z Ultra by unlocking its bootloader.
Back up your important data!
Every single file on your device will be deleted once you unlock the bootloader. So make sure you back up all your important data before proceeding with the guide given below and also make sure to move your back up files to your PC or Cloud storage because even any backup file kept on the phone will be deleted.
Check out the link below if you need any help with backing up your device.
Method 1 – Unlock Bootloader using Flashtool
Flashtool is a multi utility program for Xperia devices that does a lot of tasks in much easier ways compared to Sony’s official ways. Here in this guide we’ll be using flashtool only for the purpose of unlocking the bootloader.
Download and install Flashtool
Install Flashtool to the directory of your choice
Instructions for unlocking bootloader using Flashtool
Start/Open Flashtool
You’ll see a window asking you to connect your device in Flashmode. You can ignore the animated instruction on the screen as it’s not meant for the current generation of Xperia devices, instead follow the instructions given below to connect your Xperia Z Ultra to your PC in Flashmode
Switch off your phone
Now while holding down the Volume Down key on your phone connect it to PC using a USB cable
Your device should now be connected in Flashmode and Flashtool should show a ‘Device selector’ pop-up window
Select ‘Sony Xperia Z Ultra’ from the list of devices in the ‘Device selector’ window
Have fun!
Method 2 – Unlock bootloader using Sony’s website
Unlocking bootloader using Sony’s website would require you to first get the unlock from Sony’s website and then run a couple of fastboot commands using command prompt on your PC.
Getting the bootloader unlock key from Sony’s website
Open this link in a new tab or window → http://unlockbootloader.sonymobile.com/unlock/step1
Check for new mail on the E-mail address you provided in the form above with the subject line ‘Your requested unlock boot loader key’. Open the mail and you’ll see your bootloader unlock key.
Save your bootloader unlock key in your Notepad, a text file or anywhere you could remember and refer back quickly.
Unlocking bootloader using the Unlock Key
Now we’ll run some fastboot commands on your PC and for that you’ll need to download some fastboot files on your computer. Below is the download link:
Extract the fastboot file you downloaded from the link above and open the folder where you extract it
Now connect your phone in fastboot mode
Switch off your phone
Hold the Volume UP key on your phone and connect it to PC using a USB cable
On the command prompt window we opened in Step 2 type the command given below and hit enter. This is to verify that your device has connected properly (check the screenshot below for reference) fastboot.exe -i 0x0fce getvar version
Now you’re going to run the main bootloader unlock code. So make sure you’ve backed up your important data on the phone because once you unlock the bootloader every single file on your phone will be deleted
Paste/write the following command in the command prompt window. Do NOT hit enter yet fastboot.exe -i 0x0fce oem unlock 0xKEY
Replace the last word in the command (KEY) with your bootloader unlock key that you received from Sony via E-mail. Your command should look like this fastboot.exe -i 0x0fce oem unlock 0x636FF374683A24EF
Hit enter once you’ve put your unique bootloader unlock key in place
Have fun!
Shivam is our resident designer and web developer who also enjoys writing. He loves to meditate, drive on the freeways and hunt for snipers during his Call Of Duty playtime. Email: shivam@theandroidsoul.com