I am getting this error when I upgrade

JInstaller::install: There is already a folder called '/home/casweb1/public_html/plugins/system/sef_advance.php'. Please initially check whether:
• the Extension is already installed
• the file names in the XML file are spelled correctly
• there are no XML files listed inside the extension.xml file
• all of the files (not including XML files) are correctly listed in the extension.xml file and there are no duplicate entries
• there is an empty folder listed from a previous installation attempt


The new version does install

When reinstalling uninstall the SEF Advance plugin manually! There is a bug in Joomla 1.5.8 which makes that uninstall component function is not called so the plugin is not automatically uninstalled, it needs to be done manually due to this Joomla bug.

Can you please tell me what files to uninstall and where are they located. I am still getting plugin is installed error but i have deleted it. Thanks

When uninstalling on J! 1.5.8 uninstall the SEF Advance 2008 component, then go to plugins and locate SEF Advance system plugin, uninstall it. Then make sure directories components/com_sef/ and administrator/components/com_sef/ are deleted, if not delete them with FTP.

Then install the fresh component.

New error - Plugin Uninstall: Manifest File invalid or not found

You messed up with install / uninstall and it's partially because of this bug in Joomla 1.5.8. Send the access info (admin password and FTP) on mail and I will help you with installation. Do not post more on forum, this is specific issue.