According to a "trusted" source close to Microsoft, the Redmond-based company's forthcoming Windows Phone 8 Apollo OS update won't feature an upgrade path.

If true, this means you won't be able to upgrade your Windows Phone Mango-powered smartphone (including Nokia's flagship Lumia 900) to Apollo when this version of the Windows Phone OS launches (sorry!) later this year. Basically, you'll be stuck with Windows Phone 7.

Microsoft has responded to this rumour in a strange way, choosing to confirm all apps in its Marketplace will work with Windows Phone 8 rather than stamp on the rapidly spreading rumour about the OS upgrade path (or lack thereof).

"We have stated publicly that all apps in our Marketplace today will run on the next version of Windows Phone. Beyond that, we have nothing to share about future releases," the company said.

Earlier today, a Microsoft evangelist contradicted this rumour by stating all existing devices will be compatible with the "next major version" of the Windows Phone OS.

The Verge / WMPoweruser