Akon -- Tech Millionaire Sues -- You Hosed My Ritzy Party

Akon knows how to spoil a birthday ... pocketing $125K to sing at a rich businessman's private party in Kuala Lumpur ... then allegedly canceling two days before his performance.

Patrick Grove -- an Aussie tech entrepreneur living in Malaysia -- claims he booked Akon for the private birthday bash last April ... working out all of the logistics with Akon's people and paying $125K in advance.

But Grove says he learned two days before the event the "Smack That" singer would be a no-show ... and was told it was because Akon wouldn't be anywhere near Malaysia because his Australian tour had been canceled.