juicedata/juicefs · error

Failed to set RunAs value: %s

Error message

Failed to set RunAs value: %s

What it means

Thrown when k.SetStringValue("RunAs", "LocalSystem") fails while configuring the WinFsp service's run-as account. For drive-letter mounts the library sets RunAs=LocalSystem so the launcher starts the service with system privileges; a failed write aborts registration because the service would run under the wrong account.

Source

Thrown at pkg/winfsp/winfs.go:1256

	}

	if logPath != "" {
		err = k.SetStringValue("Stderr", logPath)
		if err != nil {
			return fmt.Errorf("Failed to set registry key: %s", err)
		}
	} else {
		err = k.DeleteValue("Stderr")
		if err != nil {
			return fmt.Errorf("Failed to delete registry key: %s", err)
		}
	}

	// RunAs NetworkService/LocalSystem
	if !asNetworkDrive {
		err = k.SetStringValue("RunAs", "LocalSystem")
		if err != nil {
			return fmt.Errorf("Failed to set RunAs value: %s", err)
		}
	} else {
		k.DeleteValue("RunAs")
	}

	//  SET "HKLM\\SOFTWARE\\WOW6432Node\\WinFsp\\MountBroadcastDriveChange" to 1
	k2, err := registry.OpenKey(registry.LOCAL_MACHINE, "SOFTWARE\\WOW6432Node\\WinFsp", registry.ALL_ACCESS)
	if err != nil {
		logger.Warningf("Failed to open registry key for MountBroadcastDriveChange: %s", err)
	} else {
		defer k2.Close()
		err = k2.SetDWordValue("MountBroadcastDriveChange", 1)
		if err != nil {
			logger.Warningf("Failed to set MountBroadcastDriveChange value: %s", err)
		}
	}

	return nil

View on GitHub (pinned to c9a67b23e8)

Solutions

1. Run the mount elevated as Administrator so the RunAs value can be written.
2. Verify the WinFsp\Services\juicefs-<alias> key exists; if the earlier steps succeeded it should — reinstall WinFsp if keys vanish.
3. Check security software or Group Policy intercepting HKLM writes.
4. Retry the mount after any WinFsp upgrade completes.

Example fix

// before (non-elevated)
> juicefs mount redis://... X:
// after
> Start-Process juicefs -ArgumentList 'mount','redis://...','X:' -Verb RunAs

// confirm HKLM write access before service registration
_, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\WOW6432Node\WinFsp\Services`, registry.SET_VALUE)
if err != nil { return errors.New("run as Administrator") }

if err := mount(...); strings.Contains(err.Error(), "Failed to set RunAs") { /* run elevated, verify WinFsp\Services key, retry */ }

When it happens

Trigger: Mounting as a network drive... precisely: asNetworkDrive == false and the RunAs registry write fails — insufficient privileges, missing service key, or registry access restrictions.

Common situations: Non-administrator shell registering a service; corporate policy blocking HKLM writes; WinFsp Services key deleted between the earlier writes and this one (uninstall race).

Understand the failure class

Background: Permission denied / not authorized / 403 Forbidden: access-control rejections when the caller lacks the required role, grant, or ownership — this error's family across 18 libraries.

Related errors

• Failed to create registry key: %s
• Failed to open registry key: %s
• Failed to set registry key: %s
• Failed to delete registry key: %s
• Failed to get current file path: %s

AI-assisted analysis of juicedata/juicefs@c9a67b23e8 (2026-09-06). Data as JSON: /api/errors/69e6d610723e50fc. Report an issue: GitHub.