Fatal error: Namespace declaration statement has to be the very first statement in the script in /home/basketb0/public_html/aut

I keep getting this message when I keep am trying to do different jobs such as put articles on my home page how do I fix this.

(
Fatal error: Namespace declaration statement has to be the very first statement in the script in /home/basketb0/public_html/autogas-scotland.com/vendor/symfony/validator/Constraints/RangeValidator.php on line 12)

Drupal version: 


Source: https://www.drupal.org/taxonomy/term/2/feed