hashicorp/nomad · error

unable to get existing service - %w

Error message

unable to get existing service - %w

What it means

Returned by serviceInstall when GetService fails to open the existing Nomad Windows service for update. Registration was detected, but the service handle needed to reconfigure it could not be fetched.

Source

Thrown at command/windows_service_install.go:203

	return nil
}

func (c *WindowsServiceInstallCommand) serviceInstall(m winsvc.WindowsServiceManager, opts *windowsInstallOpts) error {
	var err error
	var srvc winsvc.WindowsService
	cmd := fmt.Sprintf("%s agent -config %s", opts.binaryPath, opts.configDir)

	exists, err := m.IsServiceRegistered(winsvc.WINDOWS_SERVICE_NAME)
	if err != nil {
		return fmt.Errorf("service registration check failed - %w", err)
	}

	// If the service already exists, open it and update. Otherwise
	// create a new service.
	if exists {
		srvc, err = m.GetService(winsvc.WINDOWS_SERVICE_NAME)
		if err != nil {
			return fmt.Errorf("unable to get existing service - %w", err)
		}
		defer srvc.Close()
		if err := srvc.Configure(winsvc.WindowsServiceConfiguration{
			StartType:      winsvc.StartAutomatic,
			DisplayName:    winsvc.WINDOWS_SERVICE_DISPLAY_NAME,
			Description:    winsvc.WINDOWS_SERVICE_DESCRIPTION,
			BinaryPathName: cmd,
		}); err != nil {
			return fmt.Errorf("unable to configure service - %w", err)
		}
	} else {
		srvc, err = m.CreateService(winsvc.WINDOWS_SERVICE_NAME, opts.binaryPath,
			winsvc.WindowsServiceConfiguration{
				StartType:      winsvc.StartAutomatic,
				DisplayName:    winsvc.WINDOWS_SERVICE_DISPLAY_NAME,
				Description:    winsvc.WINDOWS_SERVICE_DESCRIPTION,
				BinaryPathName: cmd,
			},

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Re-run from an elevated shell
2. Run `sc.exe delete nomad`, reboot, then re-run install to take the CreateService path
3. Check the chained %w cause for the concrete SCM error code
4. Avoid concurrent installs/uninstalls of the Nomad service

Example fix

// before
nomad windows install
// after
sc.exe delete nomad && nomad windows install

out, _ := exec.Command("sc.exe", "query", "nomad").CombinedOutput()
if strings.Contains(string(out), "STOP_PENDING") || strings.Contains(string(out), "DELETING") {
	log.Println("service in transitional state; wait or reboot before installing")
}

srvc, err = m.GetService(winsvc.WINDOWS_SERVICE_NAME)
if err != nil {
	if errors.Is(err, windows.ERROR_SERVICE_MARKED_FOR_DELETE) {
		// wait for deletion to settle, then retry once
	}
	return fmt.Errorf("unable to get existing service - %w", err)
}

When it happens

Trigger: Service is registered but OpenService fails: insufficient rights, service registered under a name resolved differently, or the service handle cannot be opened due to SCM state.

Common situations: Race where the service was deleted between the existence check and open; running without elevation; corrupted service entry left by a failed prior install/uninstall.

Related errors

• unable to stop existing service - %w
• service install failed - %w
• service registration check failed - %w
• unable to configure service - %w
• unable to create service - %w

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/fcaecc09b679d3a1. Report an issue: GitHub.