J3.x:Fatal Error with PHP5.3 and Multilanguage enabled

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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.

Errors reported

Fatal error: Function name must be a string in libraries/cms/router/router.php on line 639

Versions affected

General Information

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.