Enlarge Image Net Market Share

Windows 10 didn't entice many new users last month, a new report shows.

Microsoft's current OS grabbed a 14.35 percent slice of all Web traffic in April, according to Web tracker Net Market Share. That number showed almost no growth from the 14.15 percent in March and followed several months of relatively healthy gains.

Whether this is a temporary blip or something more permanent, the weaker uptake in Windows 10 growth comes as Microsoft needs to prove it can still craft a user-friendly operating system after the hard luck of Windows 8. Windows 10 adoption is also critical to helping stem a nosedive in PC and tablet sales.

Launched July 29, Windows 10 is a free upgrade for the first year to anyone running Windows 7 or 8.1. After that, Windows 10 jumps to its full price of $119 for the Home edition and $199 for the Pro version. Microsoft needs to see strong growth in adoption before late July when the freebie ends and adoption drops off.

In March, the software giant said that Windows 10 was home to more than 270 million active devices. But Microsoft has stated that it's shooting for 1 billion devices within the two to three years of the software's release, so it's still got a way to go.

To lure more customers, Microsoft will unveil a Windows 10 Anniversary update this summer. This free update will bring improvements to the Hello login feature and the Cortana voice assistant, as well as add support for Microsoft's HoloLens augmented-reality headset.

Windows 10 wasn't the only OS to suffer last month. Windows 7's share of Web traffic dropped to 48.8 percent, the first time that number has dipped below 50 percent since April 2014. Windows XP's cut of the market fell below 10 percent to 9.66 percent. Add up all the declines, and Windows' overall share of traffic last month tumbled below 90 percent to 89.2 percent.

In the positive column, Apple's Mac OS X saw its share rise to 9.2 percent last month from 7.7 percent in March. Though its PC shipments have fallen along with the rest of the industry, Apple has been one of the few computer makers to outperform the market, according to research firm IDC.