18.04: color emoji not showing up at all in Chrome, only partially in Firefox

For anyone else having the problem, uninstalling and re-installing the font pack worked for me (Ubuntu 19.10)

$ sudo apt remove fonts-noto-color-emoji
$ sudo apt install fonts-noto-color-emoji

or just

$ sudo apt reinstall fonts-noto-color-emoji

Then restart Chrome.

Edit:

The problems comesback sometimes when Chrome gets an update, and then I have to re-install the font.

IDK if it helps but maybe copying the font into /usr/local/share/fonts will solve this for future updates:

sudo cp -r /usr/share/fonts/truetype/noto /usr/local/share/fonts/truetype/noto

I fixed it - I had to follow these instructions from 2016 I had to create ~/.config/fontconfig/conf.d/01-emoji.conf with the following text:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
  <alias>
    <family>serif</family>
    <prefer>
      <family>Noto Color Emoji</family>
    </prefer>
  </alias>
  <alias>
    <family>sans-serif</family>
    <prefer>
      <family>Noto Color Emoji</family>
    </prefer>
  </alias>
  <alias>
    <family>monospace</family>
    <prefer>
      <family>Noto Color Emoji</family>
    </prefer>
  </alias>
</fontconfig>

The bit in the original instructions about installing Noto font was unnecessary since it's installed as part of 18.04 by default.

Then run:

fc-cache -f -v

On the next restart, Chrome has color emoji.

On Ubuntu 18.04+ you can now simply install a single package: fonts-noto-color-emoji. After that, restart Chrome and it will take effect. No need for creating a manual font configuration.

^{This package is supposed to be installed on the regular Ubuntu 18.04+ desktop flavor (on a 'Recommended' level of dependency - check for yourself with apt rdepends fonts-noto-color-emoji). Some other flavors like Kubuntu (KDE) don't have this by default and require you to install it manually.}