How to fix “The system is running in low-graphics mode” error

I recently updated my Ubuntu 16.04 Linux machine through Software Updater, and when I rebooted, I got the dreaded “The system is running in low-graphics mode” error. I tried many things before finding this solution:

First of all, I have an AMD Radeon RX-480 GPU.

1. Get to a command line:

   Ctrl-Alt-F1

2. Authenticate with username and password

3. Download the latest driver from AMD:

   wget --referer=http://support.amd.com https://www2.ati.com/drivers/linux/ubuntu/amdgpu-pro-17.10-429170.tar.xz

   Note the user of referer. Without it, you won't be able to download the compressed tar.

4. Uncompress the tar:

   tar -Jxvf amdgpu-pro-17.10-429170.tar.xz

5. Run the install script:

   cd amdgpu-pro-17.10-429170
./amdgpu-pro-install -y

6. Reboot

   sudo reboot

This worked for me. My GUI came back, GNOME loaded, and I was able to live to compute another day. :)

I hope this works for you if you're in a similar situation with Ubuntu and an AMD GPU. Good luck!