Fatal error: Uncaught Error: Call to undefined function Gregwar\Captcha\imagecreatetruecolor() in /var/www/prevot/vendor/gregwar/captcha/CaptchaBuilder.php:404 Stack trace: #0 /var/www/prevot/app/controllers/contact_controller.php(21): Gregwar\Captcha\CaptchaBuilder->build() #1 /var/www/prevot/app/AppKernel.php(111): require('/var/www/prevot...') #2 /var/www/prevot/index.php(7): require_once('/var/www/prevot...') #3 {main} thrown in /var/www/prevot/vendor/gregwar/captcha/CaptchaBuilder.php on line 404