Invalid cross-device link

[shoebill]

Full Error:
ln: failed to create hard link '/media/testlink.me' => '/home/trainer/testlink': Invalid cross-device link

Executed command:
$ ln /home/trainer/testlink /media/testlink.me
ln: failed to create hard link '/media/testlink.me' => '/home/trainer/testlink': Invalid cross-device link

Reason:
Hard links cannot cross different filesystems. We know /home is a filesystem and running the mount command will also show that /media is a filesystem.

Also see: What is a hard link?