We are committed to providing a safe, secure and positive experience for our more than 300 million customers across the globe using Windows Live Messenger every month. To deliver on that commitment, beginning on August 25, we started asking our customers using versions 8.1, 8.5 and 14.0 to upgrade to the newest version of Messenger. The upgrade will provide customers with the latest software updates including code fixes and feature enhancements, as well address vulnerabilities discussed in the Microsoft Security Advisory 973882 that existed in previous versions of Windows Live Messenger.
The upgrade process will take place in a phased approach over the next several weeks:
First Phase, Optional Upgrade: The optional upgrade will happen in two stages: Starting Aug. 25, customers using versions 8.1 or 8.5 were asked to upgrade their client. Starting early Oct., all customers using versions 14.0 (but not the latest release 14.0.8089) will be asked to upgrade their client. The upgrade at this time is optional. Customers who haven’t upgraded during the optional phase will be required to do so during the second phase.
Second Phase, Mandatory Upgrade: The mandatory upgrade will happen in three stages: Starting mid-Sept., all customers using Messenger 8.1 or 8.5 will be required to upgrade their version of Windows Live Messenger. Starting late Oct., all customers using Messenger 14.0 will be required to upgrade their version of Windows Live Messenger. To ensure that we are protecting customers, those who do not administer the upgrade will not be able to sign in to Messenger after this time.
Please Note: It will take several weeks for the upgrade process to be completed, as the upgrade will be rolled out to customers over the course of several weeks.
Below are some examples of the prompts that you will encounter during the upgrade process.
Notification to upgrade.
Want to upgrade now? You don’t have to wait for the notification. In fact, we encourage you to download the updated version of Messenger right now by visiting http://download.live.com .
Full info here at Windows Live Messenger Team Blog