The certificate for omega.contacts.msn.com could not be validated. The certificate chain presented is invalid.

Getting this error from Pidgin?

It seems there is a problem with the MSN cert omega.contacts.msn.com in the current release I have installed.

To fix it on my Ubuntu machine I did the following from the command line. You need to replace $HOME with your home directory. For example if you log into your Ubuntu machine as the user “geoff” then replace $HOME with “/home/geoff“. The commands you must enter come after the ubuntu-desktop:~#.

ubuntu-desktop:~# cd $HOME/.purple/certificates/x509/tls_peers/
ubuntu-desktop:~# rm omega.contacts.msn.com
ubuntu-desktop:~# wget http://www.brainstorm.net.au/files/omega.contacts.msn.com.txt
ubuntu-desktop:~# mv omega.contacts.msn.com.txt omega.contacts.msn.com

Then I restarted pidgin 🙂

I found the fix to it here. I have also hosted the cert here.