The most frequent cause of this error is a missing or corrupted Rockchip USB driver. Windows will not recognize the device in its flashing state without these specific drivers.

Rockchip flashing protocols are incredibly sensitive to voltage drops and signal noise. Standard charging cables often fail to transmit data reliably during a flash.

Close any software that monitors serial or USB connections. Android Studio (ADB daemon), PuTTY, VMware, or VirtualBox can lock the device port, hiding it from RKDevTool. Quick Diagnostic Checklist Probable Cause Instant Fix Device Manager shows "Unknown Device" Driver missing or blocked

Alternatively, right-click and choose every time you launch it. Summary of RKDevTool Status Messages