Microsoft is not going to roll out Windows 10 Mobile to current Windows 8 or 8.1 Lumia handsets in December anymore.

Back in October, Microsoft promised that the much-anticipated update will go official just in time for the holidays.

"Broad availability of Windows 10 on other devices, including mobile phones, will begin rolling out in December," a Microsoft representative said on Facebook at the time, noting that the Lumia 950 and 950 XL would run on the OS out of the box.

However, new developments indicate otherwise. According to the latest reported statement of Microsoft, the Windows 10 Mobile update will arrive to existing Windows handsets sometime in early 2016.

"This November we introduced Windows 10 to phones including brand new features such as Continuum and Universal Windows Apps with the introduction of the Lumia 950 and 950 XL. The Windows 10 Mobile upgrade will begin rolling out early next year to select existing Windows 8 and 8.1 phones," a Microsoft spokesperson says.

The company is yet to specify which Windows 8 and 8.1 smartphones will get the update and which ones will not. The only models that are confirmed to get the upgrade so far are Lumia 430, 435, 532, 535, 540, 635 (1 GB RAM), 640, 640 XL, 735, 830 and 930.

On the bright side, we all know that Windows 10 Mobile is well under way, that is, if Microsoft doesn't go back on its word.

In other similar news, Microsoft launched the build 10586 known as the November Update and Version 1511, which is the software that came with the Lumia 950 and 950 XL. Soon after, the company released the build 10586.29, the first cumulative update for the OS. However, it was pulled out because of installation and software-related issues.

Just recently, Microsoft launched another cumulative update for the PC variant of Windows 10 Version 1511. The company, however, didn't include details, only saying that the update provides "improved functionality."