Clicking the red cross on the right corner of the pop-up box now activates the upgrade rather than closing it.
A change to Microsoft’s Windows 10 upgrade pop-up box has been lambasted by users as deceitful.
For the last six months, the company provided Windows 7 and Windows 8 users with an upgrade pop-up box asking them to either upgrade now or later.
The company asked users who wish to skip the upgrade to click the red "X" icon in the top right hand corner, which is used to close windows.
However, several users observed that clicking the red cross activates the upgrade rather than closing the box.
PC World website senior editor Brad Chacos described it as a nasty trick.
Chacos said: "Deploying these dirty tricks only frustrates long-time Windows users who have very valid reasons to stick with operating systems they already know and love."
The change took place as Microsoft labelled the update as recommended, with the majority of PC users forced to accept the update for security reasons.
The company said anyone who agrees to the upgrade can reverse the process if they want.
Microsoft said on its website: "If you click on OK or on the red "X", you’re all set for the upgrade and there is nothing further to do.
"When you close this pop up, your PC will upgrade at the scheduled time. Based on customer feedback, in the most recent version of the Get Windows 10 (GWX) app, we confirm the time of your scheduled upgrade and provide you an additional opportunity for cancelling or rescheduling the upgrade."
Microsoft is also removing the ability to block access to the Windows Store via Group Policy Editor.
The feature will still be available to those who run Education or Enterprise versions of Windows 10. Businesses that depend on this option as part of the security regime should now consider upgrading to a different version of Windows 10.
Windows 10 is running on 300 million active devices across the world. The company is ending a free upgrade offer for Windows users with previous versions of the operating system on 29 July.
Windows 10 is designed to be compatible with the hardware, software, and peripherals that users already own.
Always-enabled updates help users stay current on features and security for the supported lifetime of their device.