In this guide, we will show you the steps to fix “Failed (remote: ‘unknown cmd.’) fastboot: error: Command failed”. Recently, I was getting my hands dirty on a Tecno device [it’s quite rare that I stumble upon these devices].
And straightway I proceeded to void its warranty, aka unlock its bootloader, to be more precise, because that’s what I’m really good at! First off, I used the generic fastboot flashing unlock command, and as expected, it failed! I was greeted straightaway with the aforementioned error in the CMD window.
Turns out, this command is only available on those Tecno devices that have the MediaTek chipset, if you use this command on a Tecno. device, then the unlocking will fail, and you’ll get the Failed error message. So, how to rectify this issue and, more importantly, how to unlock the bootloader on these devices? Let’s find out.
Fix Failed (remote: ‘unknown cmd’) fastboot: error: Command Failed
Before starting, please take a complete device backup. Not to mention the fact that the device’s warranty might also get nullified. So if that’s all well and good, then let’s get started. Droidwin and its members wouldn’t be held responsible in case of a thermonuclear war, your alarm doesn’t wake you up, or if anything happens to your device, and data by performing the below steps.
You’ll need a Linux-based PC, or Ubuntu Live USB on a Windows PC [download Linux Live USB software, download the Linux Distro like Ubuntu, and then create a bootable Linux USB on a Windows PC using the software] or Ubuntu ISO on VMware Workstation Player in Windows. Once you are on Linux, let’s get started with the unlocking process.
- First off, download and install the MediaTek drivers on your PC.
- Download and extract Android SDK Platform Tools on your PC.
- Then enable USB Debugging & OEM Unlocking on your device.
- Next, open a Terminal window inside the platform-tools folder.
- Now type the below command to boot your device to Fastboot:
./adb reboot bootloader
- If this command doesn’t work, then reboot to recovery via hardware key combinations and then boot to Fastboot Mode from there.
- Then type the below command and verify if you get a serial ID:
./fastboot devices
- If you don’t, then please install the Fastboot Drivers on your PC.
- Download and extract the modified_fastboot ZIP file on your PC.
- Then right-click in an empty region and select Open in Terminal.
- Now get the Identifier Token using the below command:
./fastboot oem get_identifier_token
- The output will look something like this:
Identifier token: XXXXXXXXXXXXXXXXXXXXXXXX OKAY [ 0.022s] finished. total time: 0.022s
- Now copy this token and run the below command [replace XXX with your token]
./signidentifier_unlockbootloader.sh XXXXXXXXXXXXXXXXXXXXXXXX rsa4096_vbmeta.pem signature.bin
- You’ll get an output something along the following lines:
Identifier sign script, ver 0.10 1+0 records in 1+0 records out 61 bytes copied, 0.000324586 s, 232 kB/s Identifier sign successfully
- You should also see a signature.bin file in the modified_fastboot folder
- Now run the below command:
./fastboot flashing unlock_bootloader signature.bin
- You’ll get a confirmation screen, press Volume Down to confirm the unlocking.
- You should now get an output along the following lines:
downloading 'unlock_message'... OKAY [ 0.001s] unlocking bootloader... Info: Unlock bootloader success! OKAY [ 91.682s] finished. total time: 91.682s
- You may now boot to the OS via the following command:
fastboot reboot
- That’s it. The underlying error message has been rectified.
So these were the steps to fix “Failed (remote: ‘unknown cmd.’) fastboot: error: Command failed”. If you have any queries concerning the aforementioned steps, do let us know in the comments. We will get back to you with a solution as soon as possible.
