Official support for Joomla 2.5 ended on December 31st, 2014.
Joomla 2.5 websites will, of course, still operate after this date but security vulnerability fixes may no longer be available and this could place your Joomla 2.5 website at risk.
Joomla 2.5 will also become increasingly more difficult to support as extension developers concentrate on newer versions of Joomla and stop releasing updates for older versions.
Advice for Existing Joomla 2.5 Users
To keep your website secure, existing Joomla 2.5 website owners should update to the final release, Joomla 2.5.28 if they haven't already and plan to migrate to Joomla 3.x as soon as possible.
Apart from official support, other advantages in moving to Joomla 3.x include new features such as tags, version control and improved security with more on the way.
Migrating from Joomla 2.5 to 3.x
Moving from Joomla 2.5 to 3.x is regarded as a "mini-migration" which involves the following:
- check the hosting environment is suitable for Joomla 3.x (e.g. PHP 5.3 or later)
- run backup
- make a list of third party extensions and check that equivalents are available in Joomla 3.x
- remove any extensions that are not Joomla 3.x compatible (including templates)
- update from 2.5.x to 3.x
- install Joomla 3.x versions of third party extensions (including templates)
- test and verify that everything has migrated successfully
This process can take anything from an hour or two to a whole day or even longer depending on the complexity of the website and the availability of equivalent Joomla 3.x versions of extensions.
Migrating from Joomla 1.5 to 3.x
Joomla 1.5 website owners are in a similar position to Joomla 2.5 website owners in that Joomla 1.5 is also officially unsupported and potentially vulnerable if new security flaws are found and exploited by hackers.
Joomla 1.5 website owners can migrate directly from Joomla 1.5 to Joomla 3.x using a migration tool such as "SP Upgrade" or similar which is a litle more complicated than the Joomla 2.5 to 3.x "mini-migration". One of the main benefits for Joomla 1.5 website owners moving to the latest version of Joomla is the availability of responsive (mobile friendly) templates that weren't widely available in Joomla 1.5.