After migrating WordPress to a new server I was unable to see many of the images and the administrator could not upload.
It is import to check the permissions of your newly migrated server.
In my case I was running apache and the user of the owner of the WordPress directory was root and many of my directory/file permission were not correct.
drwxr-xr-x. 8 root root 4096 Apr 16 15:07 wordpressserver
To correct this issue do the following:
chgrp -R apache /var/www/html/wordpressserver/
chown -R apache /var/www/html/wordpressserver/
chmod 766 uploads -R /var/www/html/wordpressserver/wp-content/uploads