Microsoft's latest Windows 11 security update is triggering SSD failures during heavy data transfers, according to some reports. The issue came to attention late last week when an X (formerly Twitter) user experienced an SSD disappearing from the operating system while updating Cyberpunk 2077 on a system running Windows 11 24H2 with the KB5063878 update installed. Restarting the PC made the drive visible again, but the same error occurred when the user attempted another large transfer.
According to the user's testing, the probable bug appears during transfers of more than 50GB when the SSD is more than 60% full. In these cases, some drives become inaccessible until the system is restarted. Out of 21 SSDs tested, 12 demonstrated this behavior, and one, the Western Digital SA510 2TB, could not be recovered at all.
Other users have also described the same issue. A report spotted by Tom's Hardware cites at least eight cases in which users faced interruptions after installing KB5063878 or the earlier KB5062660 patch. One user with a SanDisk Extreme Pro NVMe drive noted that the SSD became inaccessible during a 50GB update for Honkai: Star Rail. Restarting fixed the error temporarily, but it kept happening until they deleted the KB5062660 update, after which the drive worked normally again.
At this stage, the issue does not appear widespread. While a Phison statement sent to Tom's Hardware acknowledges that some Phison-supported devices are affected, a solution has not yet been provided.
