Microsoft typically makes Windows 10 Enterprise virtual machine images available to independent developers via its developer.microsoft.com portal. For some reason, that process seems to have fallen through the cracks this month—images are available now for Microsoft's Hyper-V hypervisor but are conspicuously missing for competing hypervisors VMWare, Parallels, and VirtualBox.

Ars first became aware of this problem via impassioned tweets from Matthew Boyette, an Ars reader and independent developer whose workflow depends on these Windows 10 Enterprise VM images. The images themselves are decidedly ephemeral—they expire each month, requiring devs using the program to download new, refreshed images.

June's developer VM images expired five days ago (July 10), and despite several days of Boyette's angry tweets, the missing VM images are still missing. While VM images for Hyper-V—Microsoft's own hypervisor—were uploaded to the portal on time, devs who use VMWare, VirtualBox, or Parallels to host their virtual machines are still out of luck.

The lack of images presents a larger problem for developers who depend on them than one might expect. While it's true that a developer can still download a Windows 10 ISO and install a new VM from scratch, that doesn't replace everything the developer VMs offer. For one thing, a scratch-installed Windows 10 VM would be unlicensed and, therefore, not allow certain operating system functions (such as desktop personalization) which may be important for some developers' applications.

There's also a sizable laundry list of preinstalled and preconfigured software and features on the developer image—including the Windows 10 Software Developer Kit, Visual Studio 2019, Visual Studio Code, the Windows Subsystem for Linux (with Ubuntu pre-installed), and more. Recreating the entire environment is certainly still possible—but it represents substantial hours of work on the part of the hapless dev attempting to do so, along with plenty of additional room for error on the dev's part.

Bizarrely, the bottom of the developer image-download portal shows valid file names, lengths, and even hashes of the missing VM images—they're just not available for download.

Ars inquired about the status of the missing images Tuesday afternoon. As of Wednesday afternoon, Microsoft's PR firm has still not acknowledged the inquiry, and the images are still unavailable.