www-data is in /etc/group but not /etc/passwd. When I try to create a www-data user with
sudo adduser www-data
I get this message:
adduser: The group `www-data' already exists
This message doesn't make any sense. When I run
apache2ctl configtest
I get
chown: invalid user: 'www-data'
which also doesn't make sense. There is nothing in the apache error.log file. The apache envars file specifies that the user and group must be www-data:www-data, but Ubuntu will not let me make a user named www-data. I have tried different ways to do this, such as using the system Options dialog, useradd, usermod, etc., with no luck.
Apache2 will not run without www-data:www-data.
Any help, please.
As confusing as it might seem, you should use useradd instead of adduser
useradd -g www-data --shell=/usr/sbin/nologin www-data
This command will create an user named www-data and add it to the existing group named www-data.
The adduser command is just a helper that will call useradd and a few more commands. Furthermore useradd won't create a /home/www-data folder, which would be unwanted.
EDIT : adding the --shell prevents from directly logging in as www-data, as it must remain a system account.