File transfers over 50GB may break drives
By Veronica Wade August 19, 2025
Windows 11 24H2 users who recently installed the KB5063878 update should avoid file transfers exceeding 50GB for now. Those who haven’t updated yet should delay the security patch until more information is available. Neither Microsoft nor storage manufacturers have responded to the reports, and it remains unclear how widespread the issue is.
Twitter user @Necoru_cat has spent several days investigating an error that can make storage drives undetectable, potentially destroying massive amounts of data. Although at least one other user has reproduced the issue, all known reports have originated in Japan, and media coverage has thus far relied on machine translation; therefore, further investigation is needed.
Necoru_cat first noticed the problem when their SSD disappeared while updating Cyberpunk 2077 after installing the KB5063878 update for Windows 11 24H2, which Microsoft released last week. However, the issue might have been present in previous builds, and KB5063878 could have simply made it more likely to occur.
Further benchmarks reproduced the error in over 20 SSDs from Samsung, Western Digital, Seagate, Corsair, Crucial, and other manufacturers. Popular models, such as the 2TB Samsung 990 Pro and WD Black SN7100, are affected, and DRAMless SSDs might be more vulnerable. Because Necoru_cat could only test a small number of SSDs, the full extent of the issue remains unclear. They also observed similar behaviour in HDDs.
The problem occurs during transfers of dozens of gigabytes on storage drives with utilisation exceeding 60 per cent. Sometimes, simply rebooting resolves the issue until users attempt another large transfer. However, other cases require a full partition overwrite. In the worst instances, only reformatting the drive in Linux works.
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Necoru_cat suspects that the hardware environment could be a factor, but they cannot isolate every variable since they only have access to one system. Time will tell if other users from around the globe report the same issue, confirming that it isn’t an isolated case.
Windows 11 24H2’s KB5063878 update introduces numerous security fixes and minor user interface updates, including relocating the search bar in the Settings app to the top of the window. On Copilot+ PCs, it has been integrated with Microsoft’s generative AI chatbot, which tries to advise users when adjusting specific settings
The update also activates Quick Machine Recovery, changes the infamous Blue Screen of Death into a Black Screen of Death, and lets users enter a PC’s PIN with a gamepad.
