Windows 11 24H2: PCs with certain WD SSDs crash

The 24H2 update for Windows 11 is causing problems for some Western Digital SSDs. Since the beginning of October, there have been comments in the manufacturer forum that PCs are crashing with blue screens (BSODs). The BSOD then shows something like "Critical Process Died". The Windows event display shows errors relating to the SSD controller or NVMe driver.

After narrowing down the problem, resourceful users attribute it to the NVMe function Host Memory Buffer (HMB). This is used by modern M.2 SSDs with PCI Express connection, but without their own DRAM cache. Such SSDs use HMB to store their mapping tables from logical to physical memory addresses in the main memory. These tables are adapted with all write accesses and read out again and again, which works faster in RAM than in the NAND flash chips of the SSDs.

Western Digital's DRAM-less SSDs with HMB support include the PCIe 3.0 model WD Blue SN580 and the WD Black SN770 with PCIe 4.0, which are the models with the most problem reports.

Windows 11 24H2 increases HMB

Previously, Windows 11 (and Windows 10) always reserved a maximum of 64 MByte for the allocation table. According to the NVM Express Consortium, Windows 11 24H2 changes the allocation: The new standard minimum is either one gigabyte or one 64th of the installed RAM, whereby the operating system adheres to the supported HMB limit of the SSDs (which can still be less).

The SN580 and SN770 can allocate up to 200 MByte to the HMB. Although Windows 11 24H2 attempts to do this, errors are said to occur here at irregular intervals. There are no reports for the DRAM-less SN570, but it still only supports a small 64 MByte buffer. The error only seems to occur with DRAM-less WD SSDs with an HMB maximum of more than 64 MByte, which indicates a firmware problem for the manufacturer. Other companies do not appear to be affected.

Problem known, workaround possible

The Windows Latest website claims to have learned that Microsoft and Western Digital are working on a workaround to the problem. Until then, Microsoft is reportedly suspending the automatic update distribution to PCs with affected WD SSDs. Users should not force an update to version 24H2 using the Media Creation Tool or install a fresh version.

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Those who have already carried out the update can introduce changes to the registry as a workaround, either to completely deactivate the HMB function or to limit the buffer to 64 MByte. Both approaches should resolve the crashes; however, performance suffers if the function is deactivated completely.

The limitation to 64 MByte is particularly cumbersome. Registry scripts are available via GitHub that either deactivate HMB or limit it to 64 MByte – Use at your own risk, of course.

(mma)