To exit Test Mode, run bcdedit /set testsigning off as Admin and reboot.
| Symptom | Likely Cause | Fix | |---------|--------------|-----| | Code 10 (Device cannot start) | Driver ≥3.8 with old/clone chip | Downgrade to 3.3.2.105 | | Code 31 (Driver trying to load) | Windows forcibly loading wrong driver | Use pnputil /delete-driver to remove bad driver | | No COM port in Device Manager | Driver not installed / USB dead | Check USB tree in Device Manager (View → Devices by connection) | | Driver installs but no data transfer | Incorrect baud rate or DTR/RTS handshake | Test with loopback (TX to RX) using Serial Terminal | | Windows reinstalls broken driver after reboot | Automatic driver update enabled | Disable via Group Policy (gpedit.msc) or Registry | how to install prolific driver windows 10
Uncheck “Show compatible hardware.”