Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/66e7d5d605415b1c2e2a00f50157f655.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563