From 19th June Pidgin cannot connect to Yahoo Messenger (YM) in UBUNTU!

It seems that the guys at Yahoo are updating their servers and they are using a new authentication system.

Temporary Solution:
As a workaround until Pidgin is updated you can add cs101.msg.mud.yahoo.com in the Pager Server field. To get to this field, in Pidgin, click on Accounts, then on your Yahoo account, next on the Modify button and last on the Advanced tab of the window that just opened.

Permanent Solution for Jaunty:

Or you can update to pidgin 2.5.8 to solve this problem.

As it is mentioned here http://www.pidgin.im/download/ubuntu/

Copy-and-paste these commands into a terminal:

sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com \     67265eb522bdd6b1c69e66ed7fb8bee0a1f196a8

echo deb http://ppa.launchpad.net/pidgin-developers/ppa/ubuntu \     `lsb_release --short --codename` main | \
sudo tee /etc/apt/sources.list.d/pidgin-ppa.list

Now go to Ubuntu Update Manager, (Check & Install updates) Pidgin updates will show up along with the usual Ubuntu updates.

Note: Please dont use “username@yahoo.com” or “username@yahoo.co.in” in your Yahoo account’s username field. Use only your “username“. Right now only removing the “@yahoo.com” works. Otherwise you may encounter an error like:

“Unknown error number 1013. Logging into the Yahoo! website may fix this.”