Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/49d5e44a998dd57c72c0c33e977e99cb.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563