Fatal Error with PHP5.3 and Multilanguage enabled
From Joomla! Documentation
After an update to Joomla 3.7.3 the following Error occurs with PHP 5.3.29 on a multilingual site with language filter plugin enabled.
Fatal error: Function name must be a string in libraries/cms/router/router.php on line 639
This pertains only to Joomla! version(s): 3.7.3
What is the cause
How to fix
Update to PHP Version 5.4 or later or apply the changes from https://github.com/joomla/joomla-cms/pull/16966.