[German]Microsoft wrote that there is no evidence that the cumulative security update KB5063878 from August 12, 2025, for Windows 11 24H2 causes serious SSD problems. However, there are indications that the preview update KB5064081 from August 29, 2025, contains a "silent" fix for an SSD bug that is causing problems and broken SSDs in Japanese systems.
KB5063878 and reports of SSD issues
On August 12, 2025, cumulative update KB5063878 for Windows 11 24H2 was released (seePatchday: Windows 10/11 Updates (August 12, 2025)). Subsequently, reports emerged from Japan that this cumulative security update KB5063878 could cause serious SSD problems. When transferring large amounts of data, errors are said to occur reproducibly when saving to certain SSDs with certain controllers, resulting in data loss.
Allegedly only NAND controllers from Phison are affected
It was said that Phison's NAND controllers were more prone to these malfunctions. Since I addressed these reports in the blog post Windows 11 24H2: Does the Aug. 2025 update KB5063878 cause SSD errors? there has been much speculation about what is going on. Microsoft then investigated these reports and asked for feedback from those affected (Windows 11 24H2: Microsoft investigates reports of SSD issues caused by KB5063878).
Microsoft and Psion couldn't confirm an issuse
In the blog post Windows 11 24H2: No SSD problems caused by KB5063878 after all, I reported that both Microsoft and controller manufacturer Psion had conducted extensive tests with SSDs. In these tests, neither Microsoft nor controller manufacturer Psion were able to reproduce the errors reported in the reports caused by the KB5063878 update.
Is there still something to the SSD problem?
I had noted in my blog posts that I couldn't really assess the significance of the potential error. I was in contact with US bloggers, and it became clear that all reports referred to Japanese versions of Windows.
In my German blog readers like Chris who reported increased failure rates for SSDs running Windows 11 24H2. In this comment, blog reader Benjamin points to a YouTube video by JayzTwoCents, who claims to have reproduced the problem.
A German comment from Lars, who describes his observation, is interesting. He states that he connected six identical computers at a customer's site "last Saturday" (August 30, 2025). On Monday, September 1, 2025, four of these systems had the problem that a reboot led to the BIOS because the NVMe was no longer recognized by the BIOS operating system. Lars wrote that, contrary to many claims, Samsung was also affected, as all six computers used Samsung 990Pro 1TB SSDs.
There are also comments from another German blog reader who claims to have proven the SSD problem by installing the Japanese language pack. You can dismiss it all as a "coincidence" or take note of it as "something that could be something."
Fix for Japanese Windows 11 24H2
True to the motto "we don't need to mention a non-existent but corrected error," someone at Microsoft seems to have known more than is publicly known.
A cryptic reference to a fix
There is a German comment in the blog from MTechlerin (thanks for that, the chosen alias is quite revealing, it indicates a female person from Microsoft), who cryptically wrote, "It affects Windows 11 24H2 .4946. After updating to 24H2 .5074, most problems with HDD and SSD are fixed." I didn't really understand this when I first read the comment after it was posted, but now I've figured it out. Windows 11 24H2 Build 26100.4946, which is affected by the problem, is rolled out by security update KB5063878. Windows 11 24H2 Build 26100.5074, which should no longer have the SSD and disk issues, is available through the Preview Update KB5064081 from August 29, 2025.
And now it gets very interesting, because I became aware of the above tweets via the patchmanagement.org list. Although I don't speak Japanese, the statement says that the SSD problem caused by the August 2025 update KB5063878 will be fixed by installing the "latest Windows update." However, that is the Windows 11 24H2 Preview Update KB5064081 from August 29, 2025.
The text claims also that the cause was largely identified "yesterday" (September 1, 2025). The apparent cause is that a file system for single-byte environments (English versions) was accidentally distributed around the time KB5063878 was released. This is, of course, fatal in Japanese versions of Windows 11.
The embedded tweet from @rei_claude states: "If large amounts of data (several dozen GB) are continuously written during the installation of these two updates, certain SSDs may be irreparably damaged, rendering the computer unusable. This is not a hypothesis, but actually leads to the destruction of the SSD.
The advice is to check the update history immediately. If updates KB5062660 and KB5063878 for Windows 11 version 24H2 are already installed, users should uninstall them and restart their computer.
You can then install the preview update KB5064081 from August 29, 2025, on Windows 11 24H2. This contains the security patches from previous security updates, as well as new fixes. In this preview update, the file system required for Japanese Windows (Japanese versions, etc.) for double-byte environments is "silently" distributed again. This should fix the SSD problems. The explanation sounds logical to me—and coincides with the statements from MTechlerin quoted above. However, the observations outlined above regarding SSD problems remain open to me.
Similar articles:
Microsoft Security Update Summary (August 12, 2025)
Patchday: Windows 10/11 Updates (August 12, 2025)
Patchday: Windows Server Updates (August 12, 2025)
Patchday: Microsoft Office Updates (August 12, 2025)
Windows 10/11: Preview Updates July 22, 2025
Windows 10/11: Preview Updates August 26,/29, 2025
Windows 11 24H2: Update KB5063878 causes installation error 0x80240069
Windows 11 24H2: KIR fix for WSUS installation error 0x80240069 with update KB5063878
Windows 11 24H2: Update KB5063878 as a re-release for WSUS (August 14, 2025)
Windows 11 24H2: Does the Aug. 2025 update KB5063878 cause SSD errors?
Windows 11 24H2: Microsoft investigates reports of SSD issues caused by KB5063878
Windows 11 24H2: No SSD problems caused by KB5063878 after all
This is not just an issue with the Japanese versions of Windows.
Just check Reddit, Forums, Facebook…
it's from people all over the world.
It might be a problem with having some none English language packs of that's the case.
I had Swedish for my keyboard layout to work and for spell checking.
But the main OS language is English (US), which I switched to From English (UK) after the OS was installed.
I got corrupted data written after the KB5063878 update. It made the Windows OS unusable. It happened again after a complete reinstall of Windows, all old partitions was deleted.
BIOS was updated along with all drivers after Windows.
Well, guess I partied too early…
After getting build 5074 last week I tried to do a True Image backup of my system drive (Samsung 990Pro 4TB; German Win 11 24H2) once more and yet again it bluescreens out (now with the new black BSOD and now a different kernel error rather than UNEXPECTED_STORE_EXCEPTION), but still the drive is missing the following boot and I have to power cycle to get it back.