If you are a Windows Insider member, but have not yet updated to the current 10240 build of Windows 10, now would be a good time to do so. Microsoft is now requiring build 10240 to be installed so that Windows 10 users can access the new Windows Store.
Gabriel Aul, the head of the Windows Insider team, posted a message on the Insider Hub app for Windows 10.
"The Windows 10 Store team has been making some great fixes and improvements to reliability and performance. To ensure you are able to benefit from these important updates, starting July 24 we will be requiring Insiders who are not running the latest Windows 10 operating system to upgrade their PC; otherwise those affected will be unable to experience the Windows 10 Store. Check Windows Update to make sure you have installed the latest build and the most recent updates."
"You'll be all set once on the latest OS build 10240. Most of you will be able to experience our improved Windows 10 Store with no further action required, while a few might see a notification that says "Pardon the Interruption" and a button that will allow you to update to the latest Store version."
Aul added that the Store version number should be 2015.7.22.2 or greater.
Source: Gabriel Aul (Twitter)