Hi fadaman,

First of all, you need to enable error reporting on your Joomla so we can know the exact problem happen on your Joomla site. To enable it:

If you can enter Joomla Admin
Go to System > Global Configuration > Server Tab > Error Reporting Choose Development and Save

If you cannot enter Joomla.
Open your configuration.php and find public $error_reporting = ‘none’; and change to public $error_reporting = ‘development’;

after that open your website as usual and copy paste the error here so we can guide you better.

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If you getting this error
Warning: require_once(/home/xxxxxx/libraries/joomla/document/html /renderer/head.php): failed to open stream: No such file or directory in /home/xxxxxx/templates/xxxxxx/error.php

go to your joomla template error.php and find this

require_once(JPATH_LIBRARIES.’/joomla/document/html/renderer/head.php’);

replace that with:

if(!class_exists(‘JDocumentRendererHead’)) { $head = JPATH_LIBRARIES . ‘/joomla/document/html/renderer/head.php’; if(file_exists($head)) { require_once($head); } }

this is common problem people are having on Joomla after upgrade.