The 24H2 update for Windows 11 has been causing significant crashes on PCs equipped with some Western Digital (WD) SSDs. Many users have been reporting these issues on various online forums since early October, where computers experience Blue Screen of Death (BSOD) errors, displaying messages like "Critical Process Died." The source of these issues appears to be tied to errors related to the SSD controller or NVMe driver within the Windows event logs.

Technical Breakdown

Advanced users have traced the problem back to the NVMe function known as Host Memory Buffer (HMB). This feature is commonly used by M.2 SSDs with PCI-Express connectivity that do not include their own DRAM cache. HMB utilizes a portion of the system's RAM to store mapping tables, translating logical to physical storage addresses more swiftly than if these operations were conducted on the SSD's NAND-Flash chips.

Notably affected are models from WD's line-up lacking DRAM, such as the PCIe 3.0 WD Blue SN580 and the PCIe 4.0 WD Black SN770. These models are receiving the bulk of user complaints about the problem.

Adjustments in Windows 11 24H2

Previously, Windows 11 (and 10) reserved a maximum of 64 MB of RAM for these mapping tables. However, the 24H2 update changed this based on guidance from the NVM Express consortium. Now the minimum reservation is either 1 GB or 1/64th of the installed RAM, respecting the maximum HMB capacity of the SSDs.

WD's SN580 and SN770 support allocations up to 200 MB, but Windows 11 24H2's attempts to fully utilize this space have led to intermittent failures. Conversely, the SN570, still limited to 64 MB, has reported no issues. This predicament seems tied to a firmware problem specific to WD's DRAM-less SSDs with HMB capacities over 64 MB, not affecting other manufacturers.

Recognizing the Problem and Offering a Solution

According to information from 'Windows Latest,' Microsoft and Western Digital are actively working on solving this glitch. Microsoft has reportedly paused automatic updates for affected WD SSD-equipped PCs. Users are advised not to manually install the 24H2 update using the Media Creation Tool.

For those who have already upgraded, two registry modifications can act as stopgap solutions: fully disabling the HMB function or restricting it to 64 MB. While both methods may rectify the crashes, full deactivation can impact performance. Limiting the buffer may be tricky, but GitHub hosts registry scripts designed to either disable HMB or limit it to 64 MB — use at your own risk.

This issue was first reported by Heise Online.