Heads up to those still hanging onto a Windows Phone 8.1 device: mainstream support for the platform is set to end tomorrow, July 11.

The support end date comes just over three years since the launch of Windows Phone 8.1 to the public. At its launch, Microsoft promised 36 months of updates, stating (via Neowin):

Microsoft will make updates available for the Operating System, including security updates, for a minimum of 36 months after the lifecycle start date. These updates will be incremental, with each update built on the update that preceded it. Customers need to install each update in order to remain supported.

The most recent update to the platform was the GDR2 update, which landed in the spring of 2015. Since then, Windows Phone 8.1 hasn't seen any further major releases, with Microsoft having shifted focus to Windows 10 Mobile with its release alongside the Lumia 950, 950 XL and 550 in fall of 2015.

If you're still using a Windows Phone 8.1 handset, you may want to consider upgrading to Windows 10 Mobile if you own a compatible handset. Unfortunately, this is still a bit of a manual process, requiring users to download the upgrade advisor app and initiate the upgrade process themselves. Keep in mind that, further compounding things, the latest Creators Update Mobile release is only supported on a relatively limited subset of devices.