Over the past month, some Windows 11 users have been running into a problem with disappearing SSDs in both File Explorer and the BIOS, which started after installing the August 2025 KB5063878 update. Last week, Microsoft and Phison both washed their hands of the issue, saying it wasn’t reproduceable and that the issue wasn’t actually connected to the update in question.
Well, the problem may now be solved.
According to both Windows Report and Neowin, new findings from a Facebook group called PCDIY!—a place where Chinese PC hobbyists exchange information—indicate that it isn’t Windows that’s causing the problem but rather preliminary firmware versions on certain SSDs. These unfinished firmware versions, which were never intended for end users, appear to have been triggered by the KB5063878 update and thus began causing the problems described by users.
Phison technicians have reportedly already confirmed this, saying that tests have shown that SSDs that crashed due to the Windows 11 update KB5063878 were using preliminary firmware.
Since all SSD manufacturers that sell products with Phison controllers source their products from the original manufacturer and ship them in bulk using mass production tools, the SSDs shipped to consumers are already using the official firmware. The official firmware has been thoroughly tested and verified and has none of the anomalies that often occur with engineering firmware.
What does this all mean? If you’re using an SSD that’s disappearing after installing the August 2025 Windows 11 update, you should update the firmware. Make sure to back up all the data on the relevant SSD before initiating the firmware update.
Further reading: Common mistakes that’ll kill your SSD early
This article originally appeared on our sister publication PC-WELT and was translated and localized from German.