The Pixel 3a came out of nowhere and flexed its muscles to show the industry that you can have a great phone without a hefty price tag. Since Pixel smartphones are first-party devices straight from Google, you can be sure you'll have root access one way or another. For right now the method used to get your Pixel 3a rooted will take a few steps, but they go by real quick.
Rooting your phone with Magisk opens up the world of mods like never before with a variety of benefits. One of the best things to come from Magisk is the ability to keep Google's SafetyNet flag from being tripped, which could stop you from using certain apps. With the platform continually evolving and getting better all the time, now's the perfect time to get started.
Of course, before you can get started with modding your Pixel 3a or rooting with Magisk, you'll need to unlock your bootloader. If you haven't done so yet, visit the guide below and get your bootloader taken care of before moving on with this guide.
Once you have your bootloader unlocked and ready to go, you'll then need to download the factory image for your specific device model. Head to a computer for this part to keep things simple. Click the download link below for the newest version for either your Pixel 3a or 3a XL. You'll have to scroll down past the flashing instructions section to find where the downloads section starts.
The factory images are large in size since it includes the entire Pixel OS itself, but for this guide, you only need one particular file from the package.
After the entire factory firmware package has been downloaded onto your computer, extract the folder to any location of your choosing. Once extracted the first time, look for the only ZIP file in the folder that starts with "image" and then extract that file within the current folder to reveal all the system files.
Since you only need to grab one image file from the bunch, look for one named "boot.img" then mount your phone to your computer with a USB data cable.
Now all you need to do is transfer that boot image file from your computer to the "Download" folder on your phone.
Now that you've made it this far, you can finally start dealing with the Magisk Manager app itself. Download the latest version of the app from the link below.
The file is not very large, so the download should be rather quick, but when it's finished, tap the "OK" button followed by "Open." If you are prompted to do so, you'll need to grant Chrome the proper permissions to sideload the Magisk Manager app. Simply tap "Settings," then enable the switch for the "Allow from this source" option. Tap the back button once, and then you can tap "Install."
From the main menu of the Magisk Manager app, tap "Install" then tap "Install" again to bring up a new set of options. Choose the "Select and Patch a File" option and then allow the media permissions when prompted to do so by tapping "Allow."
From the file manager that pops up, tap the menu icon in the upper left of the screen, then select "Downloads." Select the "boot.img" file, then Magisk will begin patching it within about a minute or so. Once it finishes patching the file, go ahead and tap the back arrow to complete the process.
Now that you've got the patched "boot.img" file that you need to gain root access, you'll need to use a quick command to send the file over to your phone on a system level. You'll need to download Google's SDK Platform-Tools standalone package, which will give you everything you need without complicating things.
Now you'll need to transfer the patched boot image that you got from Magisk in Step 5 to the platform-tools folder on your computer. It should be named "magisk_patched.img" and will be located within the same "Download" folder that your original file was in. Transfer that file and the original "boot.img" file to your platform-tools folder for safekeeping in case you should need it again.
Now you'll have to put your phone into a state that it can accept the Fastboot command to push over the modified boot image file to your system. Long-press the power button, then tap "Power off" to shut your phone completely down.
When the phone turns off, hold the power button and volume down button at the same time until the Fastboot Mode main menu pops up. Make sure your phone is connected to your computer then leave the phone just like this for the next step.
At this point, your phone should be sitting on the Fastboot Mode main screen. It's almost ready to receive the proper command to send over that patched boot image file to grant your system root access. You'll need to open a command window in the platform-tools folder so that it can send the Fastboot command to the phone. Follow the link below to make sure that's all set before moving on.
Onto the final and best part — you get to execute the Fastboot command that will give your phone full root access. Type the following command, then press enter.
fastboot flash boot magisk_patched.img
Note: Mac, Linux, and Windows PowerShell users will most likely have to add a period and a slash before entering many of the Fastboot related commands (e.g., ./fastboot flash boot magiskpatched.img)._
Once the patched boot image is successfully installed, you'll need to press the volume buttons a few times until you land on the "Start" option in the Fastboot Mode menu. Press the power button to confirm your choice, and it will then reboot your phone back to the lock screen.
After your phone reboots, head back into the Magisk Manager app, then make sure you have both green check marks for "Latest Version" and "Installed Version." You'd also want to tap the arrow next to "Tap to start SafetyNet check" to ensure you pass Google's SafetyNet check.