IMPORTANT! These issues also affect Joomla! itself (Joomla! Update).
Before using Akeeba CMS Update you should be aware of some known issues which are outside our control and have to do with the way Joomla! itself and its download servers work. The same issues affect Joomla! Update, shipped with Joomla! itself: they are not unique to Akeeba CMS Update.
The update package download may fail on some servers. Some servers are actively blocking requests made to external sites. This will cause CMS Update (and Joomla! Update) to either not find any updates or being unable to download updates. Another cause for these issues can be that neither cURL nor URL fopen wrappers are available on your server. One of them is required to be enabled in PHP to be able to communicate with the update servers. Finally, if PHP or its cURL extension is compiled against a version of OpenSSL older than 1.0.1 contacting the update servers will fail since they are using HTTPS with SHA-256 signed certificates. These certificates –which ensure the security of your updates– are only supported since OpenSSL 1.0.1. Older certificates, signed with SHA-1, are no longer considered safe and are not supported by modern browsers such as Google Chrome and Mozilla Firefox. If you are on an affected server please contact your host. Meanwhile, you can download the update yourself and place it into the temporary directory of your site (typically called tmp), naming it as joomla.zip In this case, Akeeba CMS Update (and Joomla! Update, too!) will pick it up and won't try to download it from the update server.
The post-update step may timeout on some servers. Again this is something we cannot fix on our end. The post-update step is actually a .php file shipped with Joomla! itself. It tries to remove obsolete files and folders and perform database upgrade in a single page load. Due to the way it's written it is IMPOSSIBLE to break down these time consuming actions into smaller steps. As a result lower end servers, mostly shared hosting ones, may time out while executing the post-update step. In this case you can MOST LIKELY fix your site by going to Extensions, Extensions Manager, Database and click on the Fix button. Since this is part of core Joomla! we regret that we cannot provide a fix.
This version requires PHP 5.3, 5.4, 5.5 or 5.6. The rationale behind this is explained in our statement of mid-February 2013. It won't install on hosts running PHP 5.2 or earlier. PHP 5.3.4 or later is required, due to show-stopper bugs in earlier versions of PHP 5.3. Important note on reading PHP versions: PHP 5.3.20 is newer than 5.3.10 which is newer than 5.3.4. Moreover, PHP 5.4.0 is newer than PHP 5.3.4.
Due to the necessary Joomla! API changes found only in Joomla! 2.5.6 or later, this version will not install on Joomla! 2.5.5 or earlier versions. In any case, if your server doesn't meet the minimum requirements it will tell you exactly why it cannot be installed (minimum PHP or Joomla! version not satisfied).
Use with PHP 7.0 is only supported on Joomla! 3.5. Earlier versions of Joomla! do not support PHP 7 at all.
This version of our software can be installed on Joomla! 2.5.6 or any later 2.5.x release, as well as any 3.2.x, 3.3.x, 3.4.x or 3.5.x release. It is not compatible with Joomla! 3.0 or 3.1. These versions of Joomla! are old and vulnerable. If you are using them please upgrade to the latest Joomla! 3 release available from Joomla.org.