Microsoft has announced that existing Windows Phone users will not be upgraded to Windows Phone 8.

There a many positive things about Windows Phone 8 but Microsoft has stung early adopters of the platform by leaving them out of the upgrade. Instead Windows Phone 7 users will be upgraded to a new version called Windows Phone 7.8, rendering phones like the Nokia Lumia 900 obsolete. See also: Windows Phone 8 launch: as it happened.

Windows Phone 8 Start screen

Joe Belfiore, manager of the Windows Phone Program at Microsoft said: "If you currently own a Windows Phone 7.5 handset, Microsoft is planning to release an update with the new Windows Phone 8 Start screen. We’re calling it Windows Phone 7.8." Visit Windows Phone 8 release date and specs.

The news comes days after Microsoft announced two Windows 8 tablets called the Surface RT and Surface Pro. See also: Windows Phone reviews.

As Belfiore said, the version comes with the start screen which comes with Windows Phone 8. However, Windows Phone 8 apps won't run on the operating system and the answer to the question 'Will we get Windows Phone 8 later?' is simply no.

Microsoft is blaming hardware as the root of the problem meaning existing phones won't cope with the new software. "Windows Phone 8 is a generation shift in technology, which means that it will not run on existing hardware." said Belfiore.

"BUT we care deeply about our existing customers and want to keep their phones fresh, so we’re providing the new Start screen in this new update." he added.

Windows Phone 8 is expected to hit general release with the Windows 8 operating system this Autumn.