Did anyone in any region notice this? Not sure if it affected Toronto, but it's certainly an unusual occurrence.

Whatever it was, has been fixed. 

In a website post, the CBC acknowledged the issue, but did not say exactly what went wrong. 

"If you tuned into your favourite program on CBC Radio One today but instead heard fill music, alternate programming or nothing at all — it's not you, it's us. We're working on resolving a technical issue."

Not sure if such a widespread outage has ever happened before.