A fatal error has occured during the attempt to resize the "http://sengokmuhendislik.com/wp-content/uploads/2016/12/shutterstock_526166836.jpg" image.
Possible causes and their solutions (in the order of occurence) are:
/wp-content/uploads/freshizer/
directory does not exist on your webserver.
array(4) { ["type"]=> int(8192) ["message"]=> string(244) "Return type of Requests_Utility_CaseInsensitiveDictionary::getIterator() should either be compatible with IteratorAggregate::getIterator(): Traversable, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice" ["file"]=> string(123) "/home/sengokmuhendisli/domains/sengokmuhendislik.com/public_html/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php" ["line"]=> int(91) }