Microsoft released the first technical preview of Windows 10 in early October 2014, and since then, the company has upgraded it several times.
The company has released not only new versions but also many improvements that aim to give us a taste of the Windows 10.
In an announcement on the Insider Hub, Microsoft warns that old versions of Windows 10, including builds 9841, 9860, and 9879, are expiring today. Therefore, anyone still running these versions should upgrade their systems to a newer version if they want to continue using the technical preview.
Microsoft says that, in two weeks, these versions will stop rolling out completely, so users still have until April 29 to update their PC to the latest version of Windows 10.
Currently, the latest build is 10049, but it's only available to users enrolled in the fast ring. The company has said it could make it available to users in the slow ring sometime this week, along with new ISOs, but the team is still working to see if it's stable enough to push the build to a new channel.
Meanwhile, some believe that Microsoft is working on another build of Windows 10 that could see the light of day in late April, but there is no information about that specific version at this time.
