It happened last Friday, on state-owned TV station France 3:

During a prime-time live news report from the “Salon de l’Erotisme” in Nîmes (South of France), two pretty hostesses addressed the nation via a microphone that wasn’t entirely “homologated”, despite the France 3 logo attached to it.

France 3 management call it a “professional fault”, and have pulled the video from their website, but it’s still available here. The offending scene starts at 1:15, and the sound quality is surprisingly good.

Source (in French)