A US consumer group has criticized Windows 10 following multiple customer complaints following its upgrade, a recent news report said.

According to Which?, a survey of its members found out that 12 percent of people who installed the Windows 10 upgrade shared the bad news about reverting back to their own software because of some major issues that hampered the operations of their computers.

In a news article from The Register, a reported spokesperson of Microsoft said in a statement following the Which? study that the Windows 10 upgrade is "the most secure, and most productive version of Windows."

"With more than 350 million monthly active devices now running Windows 10, the vast majority of customers who have upgraded to Windows 10 over the past year have had a seamless, positive experience," the spokesperson said.

Apparently, that's not enough for Which? especially considering that Microsoft has been pestering users into doing the Windows 10 upgrade only to get the bad news.

"We rely heavily on our computers to carry out daily activities so, when they stop working, it is frustrating and stressful," said Alex Neill, Which? director of campaigns. "Many people are having issues with Windows 10 and we believe Microsoft should be doing more to fix the problem."

In related news, it seems that the Windows 10 upgrade Anniversary Edition is rolling out much slowly than first thought. Right now, only a little over 3 in 10 users of Windows 10 are getting the Anniversary Edition. A significant number is still on the fall upgrade which was released last November.