Reading package lists... Done
E: Problem executing scripts APT::Update::Post-Invoke-Success
'if /usr/bin/test -w /var/cache/app-info -a -e /usr/bin/appstreamcli;
 then appstreamcli refresh > /dev/null;
 fi'
E: Sub-process returned an error code

執行以下命令 解決：

sudo pkill -KILL appstreamcli

wget -P /tmp https://launchpad.net/ubuntu/+archive/primary/+files/appstream_0.9.4-1ubuntu1_amd64.deb https://
 
launchpad.net/ubuntu/+archive/primary/+files/libappstream3_0.9.4-1ubuntu1_amd64.deb


sudo dpkg -i /tmp/appstream_0.9.4-1ubuntu1_amd64.deb /tmp/libappstream3_0.9.4-1ubuntu1_amd64.deb

 再執行： sudo apt-get update