- Open the Windows Device Manager (on Windows 10 & 11, right-click on the Start button and select “Device Manager”).
- Expand the “Ports (COM & LPT)” section by clicking on the small arrow next to it.
- Right-click on the COM port for your RS232-to-USB adapter and select “Update Driver”.
- Reboot your PC after updating the driver software.
Troubleshooting
COM port from adapter no longer works after upgrading to Windows 11
Find out why an RS232-to-USB adapter stopped working after a Windows 11 upgrade, and whether to replace it or update its driver.
If you have an RS232-to-USB adapter with a Prolific chipset that stopped working after upgrading to Windows 11, you will likely need to buy a new one. Adapters with older Prolific chipsets are not compatible with Windows 11, but newer ones should work.
If your adapter uses an FTDI chipset, it should continue to work, although you may need to update the driver software. To do this:
Last modified on November 5, 2026