In January, Microsoft announced that Windows 10 will arrive on smartphones but not all Lumias will get the software upgrade. See also: Windows 10 hands-on review and Windows 10 for phones UK release date, price and new features.
Microsoft has already admitted that the Surface RT won't be upgraded to Windows 10 and it has now said that not all of its Lumia smartphones will either - Despite saying the new OS has been designed to run well on 'today's' Lumia phones. Find out: How to get Windows 10 now.
"Our goal is for the majority of the Lumia phones running Windows Phone 8 and 8.1 to join the Windows ecosystem along with an expected hundreds of millions of PCs, tablets and other devices running the next generation of Windows," said the firm on Lumia Conversations blog (formally Nokia Converstations).
In the blog post it confirmed an update will be definitely available for the Lumia 435, Lumia 735 and the gold-edition Lumia 930. Microsoft gave live demonstrations of features at the launch event on a Lumia 1520.
The news may be a shock for some as the firm tweeted in November last year promising upgraded for all. "We plan to upgrade all Windows Phone 8 devices to Windows 10 in the future :)," it said via the Lumia Twitter account. See also: Windows 10 screenshots.
"Like any upgrade to a new platform, not every phone will upgrade or support all possible Windows 10 features, and certain features and experiences will require more advanced future hardware," added Microsoft.
Even though Windows 10 has launched for PCs, tablets and laptops, it won't arrive on phones for a while yet. However, there is a Technical Preview which you can install if you want to try it out. What we can tell you at the moment is the official list of devices which support this, which will then support the final version.
HTC One (M8) for Windows, Lumia 430, Lumia 435, Lumia 520, Lumia 521, Lumia 525, Lumia 526, Lumia 530, Lumia 532, Lumia 535, Lumia 540, Lumia 620, Lumia 625, Lumia 630, Lumia 635, Lumia 636, Lumia 638, Lumia 640, Lumia 640 XL, Lumia 720, Lumia 730, Lumia 735, Lumia 810, Lumia 820, Lumia 822, Lumia 830, Lumia 920, Lumia 925, Lumia 928, Lumia 930, Lumia 1020, Lumia 1320, Lumia 1520, Lumia Icon.