Index: wp-admin/includes/update-core.php
===================================================================
--- wp-admin/includes/update-core.php	(revision 12413)
+++ wp-admin/includes/update-core.php	(working copy)
@@ -215,10 +215,17 @@
  * @return WP_Error|null WP_Error on failure, null on success.
  */
 function update_core($from, $to) {
-	global $wp_filesystem, $_old_files;
+	global $wp_filesystem, $_old_files, $wpdb;
 
 	@set_time_limit( 300 );
 
+	//Check for required PHP and MYSQL versions
+	$mysql_version = $wpdb->db_version();
+	$php_version = phpversion();
+	if ( ( version_compare($mysql_version, '4.1.2', '<') && !file_exists( WP_CONTENT_DIR . '/db.php' ) ) || version_compare($php_version, '4.3', '<') ) {
+		return new WP_Error('not_compatible', sprintf(__('The update cannot be installed because you do not have the correct PHP (%1$s vs 4.3 or newer) and mysql versions (%2$s vs 4.1.2 or newer).'), $mysql_version, $php_version) );
+	}
+	
 	// Sanity check the unzipped distribution
 	apply_filters('update_feedback', __('Verifying the unpacked files'));
 	if ( !$wp_filesystem->exists($from . '/wordpress/wp-settings.php') || !$wp_filesystem->exists($from . '/wordpress/wp-admin/admin.php') ||