Windows Insiders blocked from downloading preview Windows ISOs

Many Windows Insiders are unable to download the latest preview build ISOs. Non-Insider builds of Windows 11 appear unaffected, but Neowin noted that downloads of the Canary channel build 28020.1611 and the Server preview build 29531 are consistently failing. One possibility is that Microsoft is intentionally blocking access to steer users toward its own media creation utilities and away from third-party tools such as Rufus.

That explanation would fit with a desire to control how preview builds are distributed. Alternatively, the block could be a security measure. If there’s a major issue with a preview build, temporarily stopping downloads until the problem is resolved would be a reasonable step.

IP blocks and failed downloads might also be an unintended consequence of tightened security; Microsoft recently documented a Windows Hello Tampering Vulnerability that could lead to incorrect privilege assignment, so restricting access could form part of a mitigation response.

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