Although there seem to be an increasing number of things which irritate me about Google's Play Music, there's no denying that it's an incredibly convenient way to listen to music when not at home. Whether using the Android App, or playing in a browser, it makes your library available wherever you are.
It's a pity then, that Google have decided to make it such a royal PITA to upload music (I'm also not too happy about the requirement to have card details on file, even if you plan on using the free version - you should only ever need to provide card details when the plan is to actually use them, it reduces the likelihood of them being compromised).
As Google's Play Music Manager now won't run on my desktop (something I need more introduces a conflicting dependency , I figured I'd run Music Manager in a virtual machine and just point it at the right NFS share.
Turns out it wasn't quite so simple, as Music Manager returns the error 'Login failed. Could not identify your computer'.
After some digging, it's incredibly easy to resolve though.
It's not immediately clear why Google have made this decision, though presumably because you can download your entire library using the manager, but Music Manager checks the MAC address of your NIC and tries to work out what type of computer you're running.
Generally, a Virtual Machine won't have a 'real' MAC address, but will use on in a reserved range. It's for this reason that the 'Could not Identify your computer' error is returned.
Use a Real MAC
So to get Music Manager to play nicely, we just need to tell our VM to use a 'real' MAC address. Your best bet is to generate a random one.
Configure your VM to use that hardware address, reboot and Music Manager will let you log in unimpeded.
Google's help page notes that some user's have received the error whilst on physical hardware. Apparently disabling your network bridge resolves this (though if you deliberately created a bridge for a specific reason, this is hardly a solution....)