“Fix LDPlayer nRes == 0 fastpipeapi.cpp:785 Error by Turning Off VBS”
Some games in LDPlayer fail with the error "nRes == 0 fastpipeapi.cpp:785/640." The error can appear when Hyper-V cannot be fully disabled because Virtualization-Based Security (VBS) is still active. This guide checks the VBS status and tur
Before You Start
Prerequisites: Read the risk notes below. Turning off VBS changes several Windows security and developer features.; Make sure you can sign in to your Microsoft account. You may need it after the changes.; Administrator access to Windows.; Windows Hello face and fingerprint recognition, and in some cases the PIN.; Windows Sandbox.; WSL2 (Windows Subsystem for Linux).; Hypervisor Platform.
## Overview Some games in LDPlayer fail with the error “nRes == 0 fastpipeapi.cpp:785/640.” The error can appear when Hyper-V cannot be fully disabled because Virtualization-Based Security (VBS) is still active. This guide checks the VBS status and turns VBS off with the Device Guard and Credential Guard hardware readiness script from Microsoft.
## Why this works The error appears when Hyper-V cannot be fully disabled because Virtualization-Based Security (VBS) is still active. The status check confirms whether VBS is running. The readiness script turns VBS and Credential Guard off, so Hyper-V can then be turned off completely.
## What to expect The script runs in the PowerShell window and then asks you to restart. Follow any on-screen prompt during the restart. After the restart, the VBS value in System Information should read Not enabled.
## Common mistakes
- Opening a regular PowerShell window. The commands need Windows PowerShell opened as administrator.
- Pasting a folder path that does not match the folder you unzipped.
- Skipping the
dircheck. Confirm the script file is in the current folder before you run it. - Leaving out the leading period in
.\DG_Readiness_Tool_v3.6.ps1. The period is required. - Downloading the missing SIPolicy.p7b file from an unofficial site.
## Verify VBS reads Not enabled in System Information, and the game starts without the 785 error.
## Notes
- Turning off VBS and Credential Guard removes Windows protections. Weigh this trade-off before you continue.
- Read the list of disabled features above and accept the changes before you run the script.
Security note: The steps turn off Virtualization-Based Security and Credential Guard, change the PowerShell execution policy to RemoteSigned, and turn off Windows Hello and other features. Risk: Windows loses some protections against low-level attacks, and PowerShell allows more scripts to run. Revert: in Administrator PowerShell, run Set-ExecutionPolicy Restricted, which is the default on many Windows client systems. To turn VBS back on, check Microsoft’s documentation for the readiness tool’s -Enable option before you run it. Set up Windows Hello again if you need it.
## Troubleshooting
## Related