Here’s possibly why Windows 11 KB5063878 is breaking SSDs
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If you have been hit by SSD or HDD failures after installing the Windows 11 24H2 KB5063878 update, there appears to be some genuine explanation coming in about the root cause. Users have been reporting disappearing NVMe drives and severe slowdowns since Patch Tuesday rolled out last month.
Initially, Microsoft and controller maker Phison dismissed any link, saying their testing, including 4,500 hours of Phison’s own, showed no connection between the update and the failures.
But new findings suggest otherwise. As reported by Facebook group PCDIY! (via Neowin), the actual culprit may not be Windows at all, but pre-release engineering firmware lurking on certain SSDs. These unfinished firmware builds, never meant for consumers, appear to have been triggered by the update, causing the instability users described.
PCDIY! group admin Rose Lee detailed the discovery, saying Phison engineers later confirmed it in their labs. Lee explains:
PCDIY! testing has revealed that the SSDs crashing and crashing due to the Windows 11 update were using pre-release, pre-final versions of the engineering firmware. Because all SSD manufacturers selling products using Phison controllers purchase their products from the original manufacturer and ship them in bulk using mass-production tools, the SSDs delivered to consumers are already using the official firmware. The official firmware has been thoroughly tested and verified, and does not exhibit the anomalies often seen with engineering firmware.
In short, if you bought your SSD at retail, you likely have the stable firmware and nothing to worry about. Still, users experiencing problems are advised to update firmware, with a full data backup first.
Phison also added that slowdown under heavy transfers isn’t a Windows bug but the SLC cache maxing out. Fixing that requires a Secure Erase, as a simple Windows format won’t cut it.
