0x800B0109 CERT_E_UNTRUSTEDROOT — Windows Error Code

Q: What does the Windows error code 0x800B0109 mean?

It is the Win32 / NTSTATUS code CERT_E_UNTRUSTEDROOT (decimal -2146762487). Certificate chain processed but terminated in a root certificate which is not trusted. VPN certificate issue.

Q: How do I decode 0x800B0109 in PowerShell?

Run [ComponentModel.Win32Exception]::new(-2146762487).Message in any PowerShell session. For HRESULT-style codes, use err.exe from the Windows SDK or the WinDbg !error command.

Q: Where does Windows typically log this error?

It depends on the originating subsystem (Windows Update → %WinDir%\WindowsUpdate.log; AD/Kerberos → Security event log on the DC; BSOD → minidump under C:\Windows\Minidump; MSI → %TEMP%\msi*.log; WMI → Microsoft-Windows-WMI-Activity). Always cross-reference the timestamp and module name with the Application and System event logs.

Description

CERT_E_UNTRUSTEDROOT (hex code 0x800B0109, decimal -2146762487) is a Windows error-level error code in the VPN & Remote Access family. Microsoft surfaces this code through the Win32 API, the Common Language Runtime, the kernel, the event log, PowerShell, command-line tools (sfc, dism, gpupdate, sc), and Windows-side applications such as Outlook, Teams, Office, and System Center.

Certificate chain processed but terminated in a root certificate which is not trusted. VPN certificate issue.

This page documents what triggers 0x800B0109, the most common scenarios where it appears, the likely root causes, and a step-by-step troubleshooting workflow you can run against affected endpoints. It is intended for system administrators, MSP technicians, helpdesk engineers, and anyone diagnosing Windows behavior in a managed environment.

In-depth explanation

This is an error-severity code. Windows uses it to signal a failed operation that prevented the caller from completing its work. The underlying cause can range from a permissions or quota issue to a corrupted system component, missing dependency, or unreachable service.

It is part of the RAS / VPN / certificate error space. It surfaces in the Always On VPN logs, the RasMan service log, the Microsoft-Windows-NetworkProfile event log, and certificate validation traces.

The code can be looked up programmatically in PowerShell with [ComponentModel.Win32Exception]::new(-2146762487).Message (for Win32 / NTSTATUS codes that map cleanly), or with net helpmsg <decimal> for the legacy decimal range. For HRESULT-style codes, decode the facility and code with err.exe from the SDK or via the WinDbg !error command.

Common causes

VPN gateway certificate expired, revoked, or signed by an untrusted root.
Server hostname does not match the certificate Subject Alternative Name.
RAS / IKEv2 / SSTP service stopped on the client.
Firewall or ISP blocking IKE (UDP 500/4500), SSTP (TCP 443), or PPTP/L2TP.
Always On VPN profile pushed via Intune / SCCM corrupted — re-deploy.

Troubleshooting steps

Verify the VPN server's TLS / IKE certificate is trusted by the client (root CA installed, not expired, CRL/OCSP reachable).
Confirm the server hostname matches the certificate Subject Alternative Name exactly.
Restart the client services: Restart-Service RasMan and Restart-Service RemoteAccess.
Check that IKE (UDP 500/4500), SSTP (TCP 443), or the configured protocol is open end-to-end.
For Always On VPN, regenerate the device tunnel with Add-VpnConnection and re-deploy the Intune profile.

Decode in PowerShell

# Decode 0x800B0109 (-2146762487) in PowerShell
[ComponentModel.Win32Exception]::new(-2146762487).Message

# Or via WinDbg / err.exe (Windows SDK)
# err 0x800B0109

# Or net helpmsg (legacy decimal range only)
# net helpmsg <decimal>

Frequently asked questions

What does the Windows error code 0x800B0109 mean?

It is the Win32 / NTSTATUS code CERT_E_UNTRUSTEDROOT (decimal -2146762487). Certificate chain processed but terminated in a root certificate which is not trusted. VPN certificate issue.

How do I decode 0x800B0109 in PowerShell?

Run [ComponentModel.Win32Exception]::new(-2146762487).Message in any PowerShell session. For HRESULT-style codes, use err.exe from the Windows SDK or the WinDbg !error command.

Where does Windows typically log this error?

It depends on the originating subsystem (Windows Update → %WinDir%\WindowsUpdate.log; AD/Kerberos → Security event log on the DC; BSOD → minidump under C:\Windows\Minidump; MSI → %TEMP%\msi*.log; WMI → Microsoft-Windows-WMI-Activity). Always cross-reference the timestamp and module name with the Application and System event logs.

Is this code recoverable?

Critical-severity codes usually require kernel-level investigation (driver, hardware, system file repair). Error and warning codes are typically recoverable through the troubleshooting workflow on this page — start with the elevated-shell + log review steps.

Should I open a Microsoft support case for this?

Open a case if the error reproduces after applying the troubleshooting steps, particularly if it blocks production workloads, occurs across multiple endpoints, or is associated with a security boundary (BitLocker recovery, Kerberos failure, DCOM hardening, SmartScreen / WDAC). Have a fresh CBS log, minidump, or Get-WinEvent export ready before opening the case.