Name: HL 340 usb to serial adapter Driver
Author: WCH

Question 1

Install fails or rolls back?

Accepted Answer

Run the HL 340 driver installer as administrator, disconnect the adapter during install, and reboot. If Windows blocks it, use the manufacturer-signed HL 340 package, not a generic CH340 download.

Question 2

Device not detected / no COM port?

Accepted Answer

Try another USB port and cable, then check Device Manager for an unknown device or yellow warning. Uninstall the entry, reconnect the adapter, and confirm a new COM port appears.

Question 3

Version conflicts after an update?

Accepted Answer

Remove older HL 340/CH340 drivers in Device Manager, including hidden devices. Install only the latest HL 340 package, restart, then reconnect the adapter.