FAILED ERROR: Magento is already installed

We get this error when re-trying to install magento. This happens because magento stores the log of the previous installation date and before carrying out installation process again it checks for previous installations and it does so by checking the date which is stored inside the xml file.

Solution 1:

delete the app/etc/local.xml file entirely.

Solution 2:

Edit the app/etc/local.xml:

Change:

<date><![CDATA[Tue, 15 Mar 2011 15:14:24 +0000]]></date>

To:

<date><![CDATA[]]></date>

Reference:

http://www.samundra.com.np/solved-failed-error-magento-is-already-installed/439