wtfutil/wtf · critical

panic(err)

Error message

panic(err)

What it means

On Windows, NewSystemInfo shells out to PowerShell (Get-CimInstance Win32_OperatingSystem).version to read the OS build for Windows 11 detection, and panics if the command fails. This fires when powershell.exe cannot be executed or errors — missing PATH, restricted execution policy, CIM/WMI service issues, or non-Windows builds accidentally compiled with this file. It runs during construction, so it crashes startup.

Source

Thrown at modules/system/system_info_windows.go:27

)

type SystemInfo struct {
	ProductName    string
	ProductVersion string
	BuildVersion   string
}

// win11BuildNumber is the first Windows build number reported as Windows 11.
// Windows 11 kept the "10.0" major.minor version, so the build number is the
// only reliable signal Win32_OperatingSystem gives us to tell it apart from
// Windows 10.
const win11BuildNumber = 22000

func NewSystemInfo() *SystemInfo {
	cmd := exec.Command("powershell.exe", "(Get-CimInstance Win32_OperatingSystem).version")
	out, err := cmd.Output()
	if err != nil {
		panic(err)
	}

	productVersion, buildVersion := windowsProductVersion(string(out))

	return &SystemInfo{
		ProductName:    "Windows",
		ProductVersion: productVersion,
		BuildVersion:   buildVersion,
	}
}

// windowsProductVersion turns the raw "major.minor.build" string reported by
// Win32_OperatingSystem into a human-friendly product version and separate
// build number. Windows 11 kept the "10.0" major.minor version, so the build
// number is the only reliable signal available to distinguish it from
// Windows 10.
func windowsProductVersion(rawVersion string) (productVersion, build string) {
	s := strings.Split(strings.TrimSpace(rawVersion), ".")

View on GitHub (pinned to bb838c1ccb)

Solutions

1. Confirm powershell.exe is installed and on PATH: run the same command '(Get-CimInstance Win32_OperatingSystem).version' manually
2. Fix PowerShell execution policy if it blocks command execution (Set-ExecutionPolicy or use -ExecutionPolicy Bypass semantics)
3. Ensure the WMI/Winmgmt service is running (net start winmgmt) and repair WMI if corrupted
4. If running as a service, give the service account access to powershell.exe and a valid PATH
5. If the panic message is exec format/not found on Linux, you built with the wrong GOOS — rebuild for your platform

Example fix

// before (manual check fails)
> powershell.exe (Get-CimInstance ...)
'powershell.exe' is not recognized
// after
> where.exe powershell.exe  # add its directory to PATH, or reinstall Windows PowerShell

// verify the command works before the widget is constructed
out, err := exec.Command("powershell.exe", "(Get-CimInstance Win32_OperatingSystem).version").Output()
if err != nil {
    log.Printf("powershell unavailable, windows version detection disabled: %v", err)
}

func safeNewSystemInfo() (si *SystemInfo) {
    defer func() {
        if r := recover(); r != nil {
            log.Printf("system info unavailable: %v", r)
            si = nil // degrade gracefully
        }
    }()
    return NewSystemInfo()
}

When it happens

Trigger: NewSystemInfo is invoked and exec.Command("powershell.exe", ...).Output() returns an error: powershell.exe not on PATH, PowerShell blocked by policy or removed, WMI/CIM service (Winmgmt) stopped, or the binary built with the windows file on a non-Windows platform.

Common situations: Windows Server minimal installs without PowerShell, broken PATH for the service account running the app, PowerShell constrained-language/execution-policy environments, WMI repository corruption, cross-compilation mistakes including the _windows.go file on Linux.

Related errors

• pty mode is not supported on Windows
• panic(err)
• panic(err)
• panic(err)
• panic(err)

AI-assisted analysis of wtfutil/wtf@bb838c1ccb (2026-09-03). Data as JSON: /api/errors/c765318f6a57dda6. Report an issue: GitHub.