After spending the past two years in damage control mode over Windows 8, Microsoft will officially begin a new era for its OS on Tuesday, when it's expected to unveil a preview of Windows' next major version during an event focused on enterprise customers.

After the success of Windows 7, Microsoft misread the market with Windows 8 and botched the product's user interface, leaving a trail of many unhappy customers, especially in the consumer market.

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Among businesses, Microsoft encountered much resistance to upgrade, as many CIOs clung to the very stable Windows 7, and took a pass on Windows 8 and its subsequent revisions, afraid that the UI, optimized for touch-screen tablets, would confuse their users, lead them to revolt and affect productivity.

So it's not a surprise that the first look of the next generation of the OS -- referred to unofficially as Windows Threshold and Windows 9 -- will be directed specifically at businesses.

"With Windows 8, Microsoft was aiming at having a product with a good touch-first experience for consumers, and Microsoft didn't think about what would happen with enterprises," Al Gillen, an IDC analyst, said.

At the end of 2013, there were almost 715 million copies of Windows installed in businesses worldwide, and more than half -- 361.2 million -- were Windows 7, according to IDC. About 224 million were Windows XP, and almost 40 million were Windows Vista. Little over 16 million were Windows 8.

"Windows 8 was obviously not for enterprise use. It didn't give information workers an experience that let them be efficient at work. So Microsoft has to make sure that Windows 9 is good for that very important enterprise segment," Gillen said. Windows 8 fared better in the consumer market with 117.2 million copies at the end of 2013, although there it also trailed Windows 7, which had 322 million, according to IDC.

There are a number of areas which Microsoft must get right with Windows 9 in order to attract CIOs and IT managers.

The most obvious one is the user interface. When Windows 8 first came out in October 2012, many users were shell shocked not only by the radically different touch interface, called Modern, but also by the alternate traditional desktop, which was included to run legacy Windows 7 applications but lacked key familiar features like the Start button and menu. Users also complained that the process of toggling between the Modern interface and the traditional desktop was clunky and erratic.

The issue centered on Microsoft's decision to make Windows 8 an OS that could be used with both touch screens and with mice and keyboards. Microsoft took a different route from Apple, which has iOS for iPhones and iPads, and MacOS for its laptops and desktop computers, and from Google, whose ChromeOS runs on Chromebook laptops and desktops, and whose Android is designed for tablets and smartphones.

But Microsoft couldn't get the user experience right in Windows 8, so many users felt the OS was difficult and inconvenient to use, especially for those using it with a mouse and keyboard.

Although Microsoft addressed a number of complaints in Windows 8.1 and Windows 8.1 Update, it never fully fixed all problems. Thus, Microsoft now either needs to abandon the concept of a single OS that caters to touch devices and to conventional PCs, splitting it into two separate products, or else it needs to double-down on its efforts to harmonize the two interfaces.

Considering that Microsoft officials are big backers of "hybrid" Windows devices that can double as tablets and laptops, such as the company's own Surface Pro 3 computer, chances are that with Windows 9 it will stick with the single OS strategy.

If that's the case, then Microsoft needs to make sure that the Windows 9 interface is truly "adaptive" and know automatically whether the person is using, for example, a tablet, laptop or desktop PC, or a very large wall-mounted monitor, according to Michael Silver, a Gartner analyst. "This was a mess in Windows 8," he said.

Microsoft also must make the process of moving to Windows 9 smoother than the process of migrating to a new Windows version has historically been, as evidenced by the difficulties involved most recently in upgrading from Windows XP and Windows 7 to Windows 8.

For example, depending on the case, moving to Windows 8 can involve having to manually back up and reinstall data and applications, as well as reconfigure settings, a prospect which prompts many businesses to hire consultants and migration experts often at great expense, especially if a significant number of PCs are involved.

"Upgrading or keeping Windows current should be like keeping a phone current," Silver said. "It should be smarphone simple."

A related issue that Microsoft also should address is its decision to put Windows on a faster schedule of upgrades and releases, which many enterprise IT departments dislike. At minimum, Microsoft should add the option of a standard release track for enterprises that don't want, or can't, absorb a rapid pace of OS changes, Silver said. "There are a lot of organizations that don't want to be on a fast track for Windows upgrades," he said.

There have been a number of instances where customers have cried foul over this recently. For example, when it released Windows 8.1 Update in April, Microsoft also determined that Windows 8.1 users had 30 days to make the move or else they wouldn't be able to download the next batch of enhancements, bug patches and security fixes that would be released for the OS in May.

After complaints from both consumer and enterprise users of Windows 8.1, Microsoft extended the deadline, but upset customers still felt like Microsoft twisted their arm to get them to move quickly to the 8.1 Update.

To make matters more confusing and bothersome for Windows 8.1 users, Microsoft allowed those who had stayed on Windows 8 to continue to receive all security and non-security updates through January 2016.

Microsoft also needs to do a better job of keeping enterprise customers informed about the future roadmap for Windows, according to Gillen. "They haven't been clear on that with Windows 8," he said. "Enterprises need directional information from Microsoft on how the product will look like in the future."

A promising effort that could help Microsoft with its business customers is the push to unify the Windows code base and APIs, so that it will be easier for Windows commercial and enterprise developers to create tools, applications and integrations for the OS.

In April at its Build conference, Microsoft announced the ability to create "universal" applications that can run on Windows, Windows Phone and the Xbox via the new Windows Runtime architecture using Visual Studio 2013 with Update 2 or later. Developers can modify the applications for specific devices, but they don't have to write them from scratch in each case.

However, there is more to come on this effort. In late July, during Microsoft's fourth fiscal quarter earnings call, CEO Satya Nadella said that the next major version of Windows would be a "single, converged" OS for "screens of all sizes."

"We will unify our stores, commerce and developer platforms to drive a more coherent user experience and a broader developer opportunity," he said then.

An open question is what Microsoft plans to do with Windows RT, the Windows 8 version for devices that run on ARM chips. Some industry observers have speculated that Microsoft will not maintain Windows Phone and Windows RT as separate OSes.

Windows Phone had a 2.5 percent share of the smartphone OS market in 2014's second quarter, down from 3.4 percent a year prior, according to IDC. Meanwhile, Windows had a 2.1 percent share of the tablet OS market at the end of 2013, according to Gartner.

These figures show how dramatically Microsoft has failed in the past two years in its attempts to improve its position in the smartphone and tablet OS markets, which had been the main mission of Windows 8 and Windows Phone 8.

With Windows 9, Microsoft will try again to better compete against iOS and Android, while at the same time protecting the dominance it still holds of the PC OS market. And it can't afford another Windows 8-like blunder.

"Windows 9 has to be a watershed release for Microsoft to stay in the game," Silver said.

Adds Gillen: "Microsoft needs to get this one right."