ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

I have been following a manual to install a software suite on Ubuntu. I have no knowledge of MySQL at all. I have done the following installations on my Ubuntu.

sudo apt-get update
sudo apt-get install mysql-server-5.5
sudo apt-get install mysql-client-5.5
sudo apt-get install mysql-common
sudo apt-get install glade
sudo apt-get install ntp

Then I do

cd ~/Desktop/iPDC-v1.3.1/DBServer-1.1
mysql -uroot -proot <"Db.sql"

I ended up with the following error message.

ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

How may I fix it and continue?

Note: For MySQL 5.7+, please see the answer from Lahiru to this question. That contains more current information.

For MySQL < 5.7:

The default root password is blank (i.e., an empty string), not root. So you can just log in as:

mysql -u root

You should obviously change your root password after installation:

mysqladmin -u root password [newpassword]

In most cases you should also set up individual user accounts before working extensively with the database as well.

I was able to solve this problem by executing this statement

sudo dpkg-reconfigure mysql-server-5.5

Which will change the root password.

You have to reset the password! Steps for Mac OS X (tested and working) and Ubuntu:

Stop MySQL using

sudo service mysql stop

or

sudo /usr/local/mysql/support-files/mysql.server stop

Start it in safe mode:

sudo mysqld_safe --skip-grant-tables --skip-networking

(the above line is the whole command)

This will be an ongoing command until the process is finished, so open another shell/terminal window, log in without a password:

mysql -u root

mysql> UPDATE mysql.user SET Password=PASSWORD('password') WHERE User='root';

As per @IberoMedia's comment, for newer versions of MySQL, the field is called authentication_string:

mysql> UPDATE mysql.user SET authentication_string =PASSWORD('password') WHERE User='root';

Start MySQL using:

sudo service mysql start

or

sudo /usr/local/mysql/support-files/mysql.server start

Your new password is 'password'.

Note: for version of MySQL > 5.7 try this:

update mysql.user set authentication_string='password' where user='root';

I was recently faced with the same problem, but in my case, I remember my password quite alright, but it kept on giving me the same error. I tried so many solutions, but still none helped. Then I tried this:

mysql -u root -p

After which it asks you for a password like this

Enter password:

And then I typed in the password I used. That's all.