apache2 : bad user name ${ APACHE_RUN_USER }

I am using debian(sid). Just now i did dist-upgrade and my apache server has stop working. When I try to make it up I am getting bellow error.

bad user name ${APACHE_RUN_USER}

But when I do apache2ctl -S, its showing syntax is ok.

Can anybody tell me what is the reason why I am getting this error ?

Apache pulls user and group from environment.

The cause of the problem is that user and group are pulled from environment.

# These need to be set in /etc/apache2/envvars

To fix this problem, You can statically define user and group in your apache.conf

User www-data
Group www-data

It will start working. :)