Folder permissions, owner/groups
In such cases, Drupal first downloads the image to the temporary directory and then moves it to the public directory. Go to admin/config/media/file-system. Make sure that both temporary and public directories are defined and both are writeable by the web server. The easiest way to do this is to make the web server user the owner of the directory. The command is:

sudo chown -R www-data &lt;directory&gt;


where www-data is the web server user. Depending on your OS and web server, the user could be apache2 or httpd as well.