Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/93e2c2c7e2bcc4d79b523798010a5925.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563