Cron seems to complete, but I get a message stating that a file could not be created.
Do you have any idea about what is causing this?
You need to give the 777 directory permission to your temp folder. Like.... sudo chmod 777 -R /var/www/html/yoursite/sites/default/files/temp/
Please check images for more understanding. enter image description here
and command for give 777 permission to that directory like...
Sounds like a file permissions issue. Check this: https://drupal.org/node/244924
You can just change the temporary directory link found at sitename/admin/config/media/file-system to /tmp and save.