The files in the apache2 folder under etc are all locked. Last night someone said that executing this command will unlock it. sudo chmod 777 /etc/apache2
But after trying it, it still doesn’t work. The ubuntu16.04 version used
習慣沉默2017-06-10 09:50:58
You only set the permissions of /etc/apache2, you should also set the permissions of sub-files and directories
sudo chmod -R 777 /etc/apache2