Games freeze on loading: reads from the shared folder fail with error 999 #91

Description

I run games from the VMPal shared folder (Z:, VirtIO-FS). Genshin Impact 7.1 freezes on the loading screen after I click to enter the world, and once it crashed with 0xC0000005. Zenless Zone Zero 3.3 freezes earlier, while it is still loading at startup.

Both games write read errors to their logs, and the errors point at files on the shared folder.

Genshin Impact:

[2026-10-26 18:16:05.626] [FileReadCache] ReadFile failed with error: 999 fileId=-2147483637 file='...\Persistent\AssetBundles\blocks\00\25539185.blk' offset=22108764 size=63570
[2026-10-26 18:21:53.824] Shader LoadGpuProgramFromData failed! miHoYo/Avatar/Character_SRP_Frozen_General 248

Zenless Zone Zero:

Unable to read header from archive file: ...\StreamingAssets\Blocks\607492886.blk
Failed to read data for the AssetBundle '607492886.blk'.

To check whether the files or the share are the problem, I ran a small stress test inside the VM:

• 8 threads
• each thread opens one of six .blk files from the game folder
• each read is a random 4–64 KB block at a 4 KB-aligned offset
• about 70,000 reads in 10 seconds

Result: 325–345 reads fail with Win32 error 999, "Error performing inpage operation" (HRESULT 0x800703E7). The failures return immediately; they are not timeouts. The same test on C: with the same files: 0 failures in 660,040 reads.

So it is not just "many reads at once", it is "many files open at once": 8 threads on one file never failed, 8 threads on six files failed about 0.5% of the time.

The files are fine: the same .blk reads correctly when I open it alone, and the ZZZ file has a valid mhy1 header. The GPU is fine too: the D3D11 device is created (feature level 11.1), and there are no TDR/4101 events or LiveKernelReports.

Steps to Reproduce

1. Windows 11 ARM VM with a macOS shared folder mounted as Z:.
2. Install Genshin Impact 7.1 (or Zenless Zone Zero 3.3) on Z:.
3. Start the game, log in, and enter the world.
4. Genshin freezes on the loading screen; ZZZ freezes during startup loading.

Faster repro without games:

1. Put six large files (for example 50–200 MB each) on Z:.
2. Run 8 threads; each thread opens one file and reads a random 64 KB block in a loop.
3. About 0.5% of the reads fail with error 999. On C: the same test has 0 failures.

Current Behavior

Games hang on loading and sometimes crash. The logs show read failures on Z: (error 999) and, for ZZZ, a failed AssetBundle header read. The read test shows the share returns error 999 for a small part of concurrent reads, and the error rate grows with the number of files open at the same time (0% at 1 thread, about 0.5% at 8+ threads).

Expected Behavior

Files on the shared folder should read reliably, like on a local disk. The games should load and run normally. Copying them to C: works around it, but the shared folder should be usable for games.

Environment

• App version: VMPal 0.100 (100)
• Mac: MacBook Pro 16-inch (Nov 2024), Apple M4 Max, 128 GB
• macOS version: 27.0.1 (26A434)
• VM's OS: Windows 11 Pro, build 28000 (ARM64)

Log

Genshin Impact crashed with YuanShen.exe caused an Access Violation (0xc0000005) at 2026-10-26 18:21:59, right after the read errors. The ZZZ log excerpts are above.

The paths in the game logs go through a junction on C: (C:\Users\...\VMPalGames\...) that points to Z:\Games. I tested both the junction path and the direct Z: path, and the error rate is the same (~0.5%), so the junction is not involved.

Guest software: VirtIO-FS driver 100.104.104.30400, WinFsp SxS driver 20261026T074934Z, virtiofs.exe from VMPal Tools. The VM itself did not crash or stop, so there is no VM log. I can attach the full game logs and the test script if you want them.

My native language is Chinese and my English is not good, so this report was written with the help of DeepSeek V4.1 Flash.