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, then your adapter should continue to work on its latest driver software. If the adapter uses a FTDI chipset, you may need to update the driver software. To do this:
- 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.
For more info on the device manager and COM port troubleshooting, see this article.