這是因為 colab 系統最近從 v18.04 更新到 ubuntu v20.04 LTS 時引起的問題。
主要原因是，對於 Ubuntu v20.04 LTS，google-colaboratory 不再在 snap 包之外分發 chromium-browser。
解決方法: 加入以下代碼 參考-->https://colab.research.google.com/drive/1cbEvuZOhkouYLda3RqiwtbM-o9hxGLyC
%%shell
# Ubuntu no longer distributes chromium-browser outside of snap
#
# Proposed solution: https://askubuntu.com/questions/1204571/how-to-install-chromium-without-snap
# Add debian buster
cat > /etc/apt/sources.list.d/debian.list <<'EOF'
deb [arch=amd64 signed-by=/usr/share/keyrings/debian-buster.gpg] http://deb.debian.org/debian buster main
deb [arch=amd64 signed-by=/usr/share/keyrings/debian-buster-updates.gpg] http://deb.debian.org/debian buster-updates main
deb [arch=amd64 signed-by=/usr/share/keyrings/debian-security-buster.gpg] http://deb.debian.org/debian-security buster/updates main
EOF
# Add keys
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys DCC9EFBF77E11517
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 648ACFD622F3D138
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 112695A0E562B32A
apt-key export 77E11517 | gpg --dearmour -o /usr/share/keyrings/debian-buster.gpg
apt-key export 22F3D138 | gpg --dearmour -o /usr/share/keyrings/debian-buster-updates.gpg
apt-key export E562B32A | gpg --dearmour -o /usr/share/keyrings/debian-security-buster.gpg
# Prefer debian repo for chromium* packages only
# Note the double-blank lines between entries
cat > /etc/apt/preferences.d/chromium.pref << 'EOF'
Package: *
Pin: release a=eoan
Pin-Priority: 500
Package: *
Pin: origin "deb.debian.org"
Pin-Priority: 300
Package: chromium*
Pin: origin "deb.debian.org"
Pin-Priority: 700
EOF
# Install chromium and chromium-driver
apt-get update
apt-get install chromium chromium-driver
# Install selenium
pip install selenium
