Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/052c6b92b1b19172e5b9a0634c577838.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563