Updated Three people in Illinois have filed a lawsuit against Microsoft, claiming that its Windows 10 update destroyed their data and damaged their computers.

The complaint [PDF], filed in Chicago's US District Court on Thursday, charges that Microsoft Windows 10 is a defective product and that its maker failed to provide adequate warning about the potential risks posed by Windows 10 installation – specifically system stability and data loss.

Microsoft "failed to exercise reasonable care in designing, formulating, and manufacturing the Windows 10 upgrade and placing it into the stream of commerce," the complaint claims. "As a result of its failure to exercise reasonable care, [the company] distributed an operating system that was liable to cause loss of data or damage to hardware."

The attorneys representing the trio are seeking to have the case certified as a class action that includes every person in the US who upgraded to Windows 10 from Windows 7 and suffered data loss or damage to software or hardware within 30 days of installation. They claim there are hundreds or thousands of affected individuals.

The complaint enumerates a number of alleged problems with the way the Windows 10 update presents itself to Windows users, noting that it "often installs itself without any action being taken by the consumer."

Microsoft recently changed its Windows update behavior to allow for more user input. "Prior to the Creators Update, Windows 10 made most of the decisions for you regarding when updates would be installed, and didn't provide ways to tailor the timing to your specific needs," wrote John Cable, director of program management in the Windows servicing and delivery team in a blog post earlier this month.

"What we heard back most explicitly was that you want more control over when Windows 10 installs updates."

According to the complaint, Windows 10 installed itself onto plaintiff Stephanie Watson's computer without her consent and then erased data, some of it related to her work. She hired Geek Squad to repair the machine, with only partial success, and ended up having to purchase a new computer.

Plaintiff Robert Saiger, the complaint says, consented to the Windows 10 update, only to have his computer stop functioning. He lost data, then lost time and money, while incurring aggravation attempting to recover the data.

Plaintiff Howard Goldberg "elected to accept Windows 10 after declining over 6 months of daily prompts requesting him to download it." After three attempts to do so, the result was a non-functional computer and lost data.

Last June, a California woman won $10,000 after a Windows 10 update disabled her PC. In September, UK-based consumer group Which? noted that Windows 10 updates were being deployed without consent, despite Microsoft's insistence that users have a say in the matter.

Microsoft was unable to comment at time of publication. ®

Updated to add

Microsoft doesn't think much of the lawsuit. "The Windows 10 free upgrade program was a choice designed to help people take advantage of the most secure, and most productive Windows," a Microsoft spokesperson said in an email to The Register. "Customers had the option not to upgrade to Windows 10. If a customer who upgraded during the one year program needed help with the upgrade experience, we had numerous options including free customer support and 31-days to roll back to their old operating system. We believe the plaintiffs’ claims are without merit."