You have tried to install Akeeba Backup 3.5.x on Joomla! 1.5, 1.6 or 1.7. This is not possible. Akeeba Backup 3.5.x only supports Joomla! 2.5 as clearly stated in our release announcement.
Joomla! 1.5 users will still be supported for using Akeeba Backup 3.4.3 on their sites until August 2012. After that point, the Joomla! project itself will completely stop supporting Joomla! 1.5. This means that Joomla! 1.5 will become vulnerable, end-of-life software which should not be used on live sites. The Joomla! project has announced its plans for Joomla! 1.5's end-of-life back in January 2011 when Joomla! 1.6 was released. If you are receiving update emails and wish them to stop, please unpublish the System - Akeeba Backup Update Check plugin.
Similarly, we have ceased support for Joomla! 1.6 since September 2011 and ceased support for Joomla! 1.7 since March 2012, that is as soon as these platforms were deemed end-of-life. Also note that Joomla! 1.5.0-1.5.25, 1.6.x and 1.7.x all have very grave security vulnerabilities. There are instructions out there which allow any monkey with a computer to hack sites based on those ancient Joomla! releases in 5 minutes or less. If you still have a live site with a vulnerable version of Joomla!, upgrade as soon as possible. If you want to continue using a vulnerable version of Joomla! at your own risk you may use one of the unsupported versions of our components mentioned in our version compatibility page: https://www.akeebabackup.com/compatibility.html
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
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