The latest Windows 11 update is under suspicion for causing SSD and HDD disconnection issues during large data transfers. Many users in Japan have reported drives disappearing while copying files, but Phison, one of the best-known suppliers of SSD controllers, says it could not reproduce the problem after extensive testing.
Phison's Response and the Investigation Into the SSD Failures
Shortly after Microsoft released update KB5063878 for Windows 11 24H2 on August 12, users in Japan began reporting that their SSDs and HDDs became undetectable after transferring more than 50GB of data. In most cases, restarting the computer brought the drive back, but the problem returned during later copy operations. Some drives even required a format or a rewrite of the partition table to work normally again.
Amid the wave of reports, Phison was the first company in the industry to announce that it was working with Microsoft on an investigation. However, in a report sent to Wccftech, Phison said that after 2,200 test cycles and more than 4,500 hours of performance measurements, it did not observe any of the reported failures. The company also recommended that users fit NVMe SSDs with a heatsink to reduce the risk of thermal throttling, although the issue is not believed to be entirely related to temperature.
Phison also rejected claims that its SSD controllers have a compatibility problem with the new update. A document circulating online alleged a serious defect affecting the company's drive lineups, and Phison has denied it as fake. So far, although the cause has not been identified, Phison remains the only storage manufacturer to have spoken out officially about the issue.
Users Should Be Cautious When Installing KB5063878
Alongside the official investigation efforts, many other users, especially in Japan's tech community, are still running into similar problems after updating. The Twitter account @Necoru_cat, the first to spot the issue, is now in direct contact with Microsoft to clarify the cause. They also deny having skipped a heatsink, which strengthens the theory that the problem may lie in software rather than hardware.
Besides Phison, several drive lineups from Samsung, Western Digital, Seagate, Corsair, and Crucial have also reportedly hit similar failures, particularly when used capacity exceeds 60% of the drive's total capacity. However, these companies have not yet made an official statement on the matter.
Until there is a firm conclusion, users running Windows 11 version 24H2 should consider delaying the KB5063878 update or limiting large data transfers, especially on drives that run hot or are nearly full.
Updating the operating system is necessary for security and performance, but it is also worth weighing the real-world risk, especially with patches that may affect hardware. Keep an eye on information from manufacturers and Microsoft so you can decide how best to handle your own system.
