Microsoft announced the update to Windows 10 mobile won't be including mobile phones with 512 of RAM. However, users of old Lumia phones can still access the beta version at the risk of instability.

Apparently, Microsoft took note of users' feedback to the Windows 10 mobile update particularly when they commented that the experience didn't meet the expectations.

This wasn't the first time that Microsoft disappointed users, PC World observed, particularly when it announced in November 2014 that all Lumia Windows Phone 8 will avail of the upgrade.

"In January 2015, Microsoft said it would aim to support 'the majority of Lumia phone running Windows 8 and 8.1,' but six months later said the upgrade would only extend to devices running the latest Lumia Denim software," it said.

The Verge has the complete list of Lumia phones that will get the Microsoft Windows 10 mobile update. These are the following:

Lumia 430

Lumia 435

Lumia 532

Lumia 535

Lumia 540

Lumia 635 1GB

Lumia 636 1GB

Lumia 638 1GB

Lumia 640

Lumia 640XL

Lumia 730

Lumia 735

Lumia 830

Lumia 930

Lumia 1520

The user of Lumia wouldn't have reacted so much if Microsoft had been upfront about the Windows 10 mobile update.

"Windows Phone 7 handsets were never upgraded to Windows Phone 8, and Microsoft set the expectation this time that history wouldn't repeat itself," it said. "Another broken promise is bad news for a mobile operating system that is practically dead, and once again Microsoft has angered its small but loyal base of Windows Phone users."