apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName ... waiting apache2:

I upgraded to ubuntu 14.04 yesterday. But after restarting PC , this message continues to appear in a black screen after the ubuntu loading screen and don't go away and ubuntu doesn't start I can do nothing about this. what should I do? I tried logging in from other terminals and do asm here but still nothing

This can be overcome by two way.

1. Add ServerName localhost as the last line in /etc/apache2/apache2.conf file.

2. Create a file named /etc/apache2/conf-available/servername.conf and add the string ServerName localhost inside and save it. Create a soft link under /etc/apache2/conf-enabled as follows

   ln -s /etc/apache2/conf-available/servername.conf .
   # or
   a2enconf servername
   

and restart the server.

The string localhost can be replaced with any valid domain name (ie. example.com).

A third way is to configure your computer's hosts file:

127.0.0.1       localhost
127.0.1.1       servername.domain.com       servername

Another way of performing the second option suggested by ccsen is the following:

1. Create a file in /etc/apache2/conf-available/ with any desired name. servername.conf is a suitable option.

2. Add the following line to the created file: ServerName yourservername. yourservername can be set to anything you want.

3. Then run the following from a terminal: sudo a2enconf servername (assuming you called the file added to conf-available on step 1 'servername.conf').

4. Finally, run the following from the terminal: sudo service apache2 reload

Although both methods achieve the same result, I believe this one is cleaner since apache takes care of the symlinks and enabling the configuration.