If you want to use Windows 10 on a Mac with either Parallels Desktop or VMware Fusion, you’ll have to strongly consider buying a new version of your virtualization software of choice.

Parallels on Wednesday this week is releasing its latest upgrade, Parallels Desktop 11 for Mac, with perpetual licenses costing $79.99 per device (or $49.99 if you're upgrading from version 9 or 10). VMware should be following up soon with its next version, Fusion 8.

You may have spent money on either Parallels 10 or Fusion 7 just a year ago, but that year-old software will only provide bare-bones support for Windows 10, which Microsoft released last month.

A big selling point of Parallels is its “Coherence" mode, which lets you run Windows applications on a Mac as if they were native Mac applications. With Coherence Mode or VMware Fusion’s analogous Unity, each Windows application gets its own window, making it feel like you’re using just one operating system even though you’re actually using applications from both Windows and Mac.

But without Coherence or Unity mode enabled, all Windows applications are isolated in a single window that contains the whole Windows operating system. That’s the situation with Windows 10 on the year-old editions of Parallels and Fusion. You can run Windows 10 in a single window, but Coherence and Unity modes are crippled.

“With Parallels Desktop 10, we offer full support for Windows 10 in full-screen and window mode, but we do not in Coherence mode and that will not be changing,” Parallels spokesperson John Uppendahl told Ars in a phone interview.

Upgrading to Windows 10 from previous versions of Windows is free, and therefore quite tempting. But trying to use Windows 10 in Coherence Mode on Parallels 10 leads to things like this:





Things were slightly different if I changed a setting to make Parallels think I was running Windows 8.1, allowing me to turn on the "Windows 7 Look." This involves running Stardock's Start8 and ModernMix applications, which are bundled with Parallels. With this setup, opening the Start menu wouldn't take me out of my primary desktop, but it was partially hidden by the Mac's dock, and trying to search for applications in the menu simply closed it. It was possible to open Metro/Modern applications on the Mac's primary desktop, but after minimizing an application I wasn't able to re-open it by clicking its dock icon.

Naturally, Parallels has new features in version 11 that it wants users to pay for, such as integration with Microsoft's Cortana virtual assistant and a new power-saving travel mode. Version 11 also strips some developer-focused features out of the basic edition and puts them in a "Pro" edition that can be pricier depending on how often you like to upgrade; more on that later.

Parallels says offering any Coherence support for Windows 10 on last year’s version is too difficult. Even a working Start menu and the ability to use Windows applications as if they were Mac ones isn't supported.

“Truly speaking, that requires a lot of work for us,” said Parallels VP of Desktop Virtualization Nick Dobrovolskiy.

Although the Windows 10 Start Menu looks similar to the one in Windows 7, Microsoft has “significantly changed” how it works on the back end, he said.

The situation is similar on VMware Fusion 7. I wasn't always able to put Windows 10 into Unity mode, but when I successfully did so the software placed this giant gray mass over my Mac screen:

VMware is “aware of some limitations with regards to Windows 10 and the Unity view mode,” a company spokesperson told us, adding that single-monitor configurations work better than multiple-monitor ones. “There are some fundamental changes that Microsoft made to how the Windows 10 desktop is drawn that we are actively working to adapt to. Fusion 8 improves upon this situation dramatically, and we look forward to sharing more of the great new features we have in store with you soon.”

VirtualBox, the free, open source virtualization software from Oracle, hasn’t been updated to run Windows 10 on Mac in its version of Coherence (VirtualBox calls it “Seamless" mode). We’ve asked Oracle when it plans to add that support and will provide an update if we get one.

UPDATE: Oracle told us that it made some changes for Windows 10 in VirtualBox 5.0.2 but it still considers Windows 10 support to be a "tech preview," both as a host and guest operating system. "We expect to provide formal support within the next few Oracle VM VirtualBox 5.0 maintenance releases," Oracle said. "Regarding Seamless mode—that is also planned to work with Windows 10 once its support is announced."

Decisions...

If you like keeping Windows separate from Mac, there's no problem. You can upgrade to Windows 10 without a second thought as it should work just fine on VirtualBox or previous versions of Parallels and VMware.

But if you like having Windows and Mac integrated, you have a decision to make. If you’re happily using Windows 8.1 on last year’s version of Parallels or VMware, there’s nothing wrong with not upgrading. You’ll still be able to use Microsoft Office and just about any other Windows applications you desire on your Mac.

If you want Windows 10 and that “new” Start Menu and integration with Microsoft’s Cortana, maybe it’s worth paying Parallels or VMware for their latest software. But if that’s your plan, it’s worth doing a free trial of the new software instead of paying to upgrade immediately, just in case you run into bugs. (Parallels offers a two-week free trial, which should be available at this link.)

It's not uncommon for the first release of a major new version to have bugs for the first few weeks or so. That's been the case with Windows 10 itself.

When I upgraded to Parallels 10 a year ago, the virtualization software kept giving me critical error messages for no apparent reason. I also had constant trouble with Microsoft Outlook e-mail messages disappearing behind the main Outlook window. In both cases I contacted Parallels support; while they weren’t able to fix my problems immediately, they did identify a problem at “the code level” that was causing the weird Outlook behavior.

The bugs finally went away after a few months and a few updates, and now Windows 8.1 is working quite well on Parallels Desktop 10. I've learned that waiting is often the best course.

Parallels didn’t offer us early access to version 11, but gave us a rundown of new features:

Performance improvements for Windows launch and shutdown, file operations, and suspension of virtual machines.

"Always on Cortana" lets users control either Windows or Mac applications with Microsoft's new virtual assistant.

Travel mode extends battery life "up to 25 percent by temporarily shutting off select resources that drain power."

The Mac's Quick Look feature (double tap the space bar to preview a document) is extended to Windows files.

Force Touch gesture support that enables Quick Look or looking up the definition of a word, on Macs with the appropriate trackpad.

When right-clicking a Windows application icon in the Mac dock, the user can see recent documents in the menu or create new ones.

Mac location services are made available to Windows applications.

Synchronization of volume between OS X and the virtual machine.

Easier method to make a Windows application the default application for opening a specific file type.

Developer features now restricted to “Pro” edition

Parallels also has a new "Parallels Desktop 11 for Mac Pro" edition aimed at developers and business users. This is available only with a subscription, costing $99.99 per year for new customers. Anyone upgrading from Parallels 9 or 10 can get the Pro version for $49.99 per year. With the subscription, you can upgrade to future versions while paying the same amount each year.

Oddly, upgrading from Parallels 9 or 10 gets you the $49.99 yearly pricing indefinitely, but new customers or those upgrading from version 8 or earlier have to pay $99.99 every year going forward. "Parallels Desktop 9 and 10 customers can upgrade to a special offer of Parallels Desktop for Mac Pro Edition for $49.99/year for life, instead of the regular $99.99/year price," Uppendahl told Ars. "The Pro Edition is $99.99/year for new customers, including subsequent years."

This Pro edition includes some features that used to be available in the basic version of Parallels. Last year's version of Parallels allowed virtual machines with up to 16 virtual CPUs and 64GB of RAM. Now only the Pro edition can make virtual machines that big; the non-Pro edition goes up to 4 CPUs and 8GB of RAM.

"For regular users, we found that what we are putting in Parallels Desktop 11 is more than sufficient," Uppendahl said.

Linked clones and nested virtualization for Linux guests, both available in the basic Parallels last year, are now restricted to "Pro."

New features for the Pro edition include integration with developer tools Docker, Visual Studio, Chef, Jenkins, and Vagrant. Macs can share business cloud storage with Windows with the Pro edition's support for Box and the business editions of Dropbox and OneDrive.

Other Pro features include "Additional user profiles for developers, power users and testers for optimal configuration for their particular scenarios; Advanced networking tools and configuration for virtual networks to test complex networking scenarios, including the ability to simulate some network instabilities; Headless mode for running virtual machines in the background without user interface; and 24/7 phone and email support," Parallels said.

Finally, Parallels has a new business edition that includes all the Pro features plus centralized management of virtual machines, a Web-based license management portal, business-class support, and the ability to enforce security policies on USB devices. The business edition is available for $99.99 per year.