Windows 11 Cumulative Update KB5063878: SSD Issues [Fixed]

Over the past few months, Windows 11 Cumulative Update KB5063878 has been repeatedly mentioned in Reddit threads, Microsoft Q&A posts, tech forums, and tech-press reports.

System administrators and power users have described that many SSD-related failures that they feel are linked to this update. To be clear though, Microsoft has not confirmed that KB5063878 directly causes SSD corruption.

At the same time, the sheer volume and technical consistency of user reports mean this cannot be dismissed as random coincidence either.

What Is Windows 11 Cumulative Update KB5063878?

Windows Update KB5063878 is an optional cumulative update released on August 12, 2025, for Windows 11 version 24H2 (OS Build 26100.4946).

KB5063878 officially includes:

• Security fixes for the Windows operating system
• A Servicing Stack Update (SSU), which affects how Windows installs future updates
• A fix for delayed sign-in on some new devices
• Version updates to certain AI components

There are no documented changes to SSD handling, NTFS, disk firmware interaction, or storage drivers. Nothing in the release notes would obviously explain an SSD suddenly turning RAW or dropping offline.

Note: KB5063878 is not a critical or forced update. In most cases, it installs only if:

• You enabled “Get the latest updates as soon as they’re available.”
• You manually installed the update.

What SSD Issues Are Being Reported After Installing Windows Update KB5063878?

Based on aggregated posts from Reddit, Microsoft forums, and admin communities, these are the five most common SSD-related symptoms.

1. SSDs or HDDs Suddenly Appearing as RAW in Disk Management

This occurs when the NTFS metadata (which is like the internal “map” that tells Windows where your files are) becomes unreadable or misaligned. The symptom here is that when you try to access your drive, Windows gives the warning, “You need to format the disk before you can use it.”

2. Repeated chkdsk Prompts After Reboot

You face repeated chkdsk prompts every time you reboot. Continuous chkdsk operations on a failing SSD can actually accelerate metadata loss.

3. Volumes Flagged as “Dirty”

If you check the status manually in the Command Prompt using the command fsutil dirty query [drive letter]:, Windows confirms the volume is Dirty.

4.Unreadable Files

Interestingly, some users report that folder names remain visible, but the files inside are unreadable or throw “Access is denied” errors.

5. SSD Disappears

The SSD may temporarily disappear from the File Explorer or start throwing SMART errors. In high-stress situations, even SMART data (the drive’s internal health monitoring and reporting system) becomes unreadable, returning “N/A” or “Device Not Found.”

Common Scenarios When SSD Issues Appear Due to Windows Update KB5063878

The recent cases of SSD data loss after installing Windows updates that we have handled, as well as the forum discussions on the issue, both suggest a specific threshold where these issues peak.

• Drives that are more than 60% full seem more susceptible.
• Many failures occur during massive data writes, such as a 50 GB game installation.

Also, early reports focused on DRAM-less and Phison SSDs, but later analysis shows reports spanning multiple controller families and brands, including Kingston, Crucial, WD, and others.

Microsoft’s Position on KB5063878 and SSD Issues

Microsoft has acknowledged that it is aware of reports describing SSD and HDD issues on systems where KB5063878 is installed. It has also stated that it is investigating these reports in coordination with hardware partners. However, Microsoft has not confirmed a direct causal link between Windows 11 Cumulative Update KB5063878 and SSD corruption or failure.

Why Is the KB5063878 Update Corrupting Drives: Technical Theories

Since there is no “official” bug fix yet, the technical community has been dissecting the Windows 11 storage stack. At Stellar, we align with three theories that explain the KB5063878 SSD issue.

1. Storage-Stack Write-Ordering Regression

The most prominent theory is that KB5063878 altered how Windows 11 handles write-back caching and Flush/FUA (Force Unit Access) commands.

To understand this, imagine your SSD has a “waiting room” (the cache) and a “vault” (the NAND storage).

• Write-back caching is when Windows tells you a file is saved as soon as it hits the “waiting room,” even though it hasn’t reached the vault yet.
• Flush/FUA are the “emergency orders” Windows sends to force the SSD to move data from the waiting room into the vault immediately—specifically for the “map” (metadata) that tracks where your files are.

The theory is that this update introduced a regression where these emergency orders are being delayed or sent in the wrong order. If Windows updates the “map” but the power blips or the system hangs before the actual data is in the vault, the map becomes a lie, which is why your drive suddenly appears as a RAW partition.

2. DRAM-Less HMB Exhaustion

Many modern SSDs are “DRAM-less,” meaning they don’t have their own dedicated memory chips. Instead, they use a small slice of your system’s RAM (called the Host Memory Buffer, or HMB) to store their address maps.

If the KB5063878 update causes I/O queues to “bloat” (storing too many pending commands at once), it can exceed the HMB’s capacity. When the SSD loses track of its own map because the HMB is overwhelmed, the controller panics. This leads to the SSD disappearing from Windows as it enters a protective hardware shutdown to prevent data collisions.

3. The “Engineering Firmware” Theory

A third explanation is that some retail SSDs may have shipped with pre-release or engineering firmware rather than hardened production builds. Such firmware can behave normally under typical workloads but crash under unusual I/O patterns.

What to Do If You Have Installed Windows Update KB5063878

If you’re dealing with a Windows KB5063878 update SSD error, what you do next can make the difference between recoverable data and permanent loss.

But first things first: if you’ve not installed KB5063878:

• Do not rush optional cumulative updates on production systems.
• Disable “Get the latest updates as soon as they’re available.”
• Ensure you have verified backups before applying any major Windows updates.

1. If You Have Installed KB5063878 and Your System Seems Fine

• Monitor closely for early warning signs like:
  • Unexpected chkdsk runs
  • Event Viewer disk or NTFS errors
  • SMART data becoming unavailable
• Avoid:
  • Stress tests
  • Very large write jobs
  • Filling SSDs close to capacity

2. If Your SSD Shows Corruption or Disappears After Installing KB5063878

This is the most important part. If a drive turns RAW, goes DIRTY, or vanishes:

• Stop using it immediately.
• Do not format, initialize, or reinstall Windows on it.
• Do not repeatedly retry writes “to see if it fixes itself.”

Each write can overwrite metadata that is still recoverable.

If your drive remains RAW or is invisible to the system after a cold boot, the issue has likely progressed beyond a simple software fix. This is when you should contact Stellar’s SSD Data Recovery Service.

At Stellar Data Recovery, we treat SSD incidents following Windows updates as mixed logical-system failures. Recovery is done by:

• Working only on forensic images, never on the original drive
• Reconstructing NTFS metadata structures rather than relying on live repairs
• Avoiding actions that trigger SSD firmware garbage collection or wear leveling during recovery

If your data matters, the safest step is to pause, preserve the state of the drive, and seek professional SSD data recovery before attempting fixes that look simple but cause permanent damage.

Right now, the safest position is neither panic nor dismissal, and we hope this guide has helped you decide your next steps.

While KB5063878 has drawn attention to update-related storage risks, it is not the only scenario where SSDs fail unexpectedly. Many users encounter SSD errors that appear without warning and require a very different recovery approach. Below are some related articles you may encounter:

• How to Fix SSD Not Detected by BIOS or OS
• How to Fix SSD Bad Blocks and Reallocated Sectors
• Common SSD Errors and Issues—Causes, Fixes and Solutions
• How to Fix SMART Errors on SSD
• How to Fix Read/Write Errors in SSDs
• Slow SSD Performance: Causes, Fixes, and Data Recovery Options