File: admin/cli/install.php, Line: 330 $dataroot = clean_param($options['dataroot'], PARAM_PATH); if ($dataroot !== $options['dataroot']) { $a = (object)array('option' => 'dataroot', 'value' => $options['dataroot']); cli_error(get_string('cliincorrectvalueerror', 'admin', $a)); } Function clean_param removes colon from $options ['dataroot'] and replaces slash with backslash. As a result $dataroot will not be equal to $options ['dataroot'] and installation will stop with error.