Windows 10 - U232 P9 Driver

Look for a yellow exclamation mark next to or USB-Serial Controller . Right-click the unknown device and choose Update driver . Select Browse my computer for drivers .

| Problem | Solution | |--------|----------| | | Legacy chip + new driver → Uninstall & use v3.3.2.105 | | Code 31 (Device not working) | Windows blocked driver → Disable signature enforcement | | No device detected | Try different USB port / cable. Some adapters are faulty. | | Data errors / garbage output | Lower baud rate or change flow control to None. | | Clone chip | v3.3.2.105 works but may be unstable. Consider buying FTDI-based adapter. |

Double-click it and change the value data from 1 (automatic) to 0 (device drivers are never installed from Windows Update).

Check the box next to the Prolific/U232 driver update to permanently prevent Windows from downloading it. Troubleshooting Persistent Connection Issues u232 p9 driver windows 10

The U232-P9 is a popular, affordable USB-to-Serial (RS-232) adapter, which is essential for connecting modern laptops (that lack serial ports) to older devices like GPS receivers, modems, routers, and scientific instruments. While you can find these adapters online for just a few dollars, the challenge often begins when you try to use them with modern versions of Windows. Users commonly report the device appearing as Prolific USB-to-Serial Comm Port in Device Manager, but with a prominent yellow exclamation mark indicating it isn't working.

Most U232 P9 adapters rely on the Prolific PL2303 chipset. Windows 10 often automatically installs the newest driver version, which intentionally disables older or "clone" chips to prevent piracy. This results in a yellow exclamation mark in your Device Manager and a message stating "This device cannot start (Code 10)." Step 1: Download the Correct Driver

How to Install and Troubleshoot the U232 P9 Driver on Windows 10 Look for a yellow exclamation mark next to

Uncheck "Show compatible hardware" if needed, look for an older driver version (2015 or earlier), select it, and click . Disabling Driver Signature Enforcement

Look for the compilation (often version 2.10 or higher).

Since these drivers are old, Windows 10 may block them. You might need to temporarily disable driver signature enforcement to complete the installation. Alternative Chipsets | Problem | Solution | |--------|----------| | |

Locate the U232-P9 (often listed under or Other Devices with a yellow warning triangle). Right-click the device and select Update driver .

Right-click your problematic U232 P9 / Prolific device and select .