A key part of Microsoft's app store is broken ahead of Christmas

In-app purchases are broken in the Windows Store, according to $4.

The issue, which was $4, appears to be affecting a number of Windows Store users who try and buy content within an app.

This is a problem for developers ahead of Christmas an in-app purchases are a key way of making money. The app can be free, making it more appealing, and additional features can then be bought.

Developers such as Supercell, the studio behind "Clash of Clans," makes $4 from in-app purchases.

Developers first highlighted the issue on December 18 and it appears to be persisting until today for many developers and users. $4, the Windows Store has over 350,000 apps, many of which are supported by in-app purchases.

Business Insider has reached out to Microsoft to ask about the issue. We will update the post when we hear back.