How to update RC from 0.3.1 to the latest

[VeloTaurus]

I was asked to maintain the local cycling club site and update the software.
I looked through index.php code and found that version 0.3.1 was installed. I think that's a very old version, isn't it? I have not met with RoundCube before, and I don't even know if I can upgrade this version to the latest one without any intermediate steps.
Tell me how should I act to upgrade this old version to the latest?

[SKaero]

Well that is rather old, I'm surprised it still works. Theoretically you should be able to do a standard upgrade https://github.com/roundcube/roundcubemail/wiki/Upgrade just make sure to follow the steps outlined but first it would be a good idea to make sure the system will meet the current server requirements https://github.com/roundcube/roundcubemail/wiki/Install-Requirements since Roundcube 0.3.1 was released in October 2009 and currently Roundcube requires PHP 5.4.1 or greater and PHP 5.4.1 wasn't even released until 2012. Remember to backup!