Serial includes built-in support for the Prolific PL2303 family of bridge chips.
Due to the architecture of macOS, when a kernel driver binds to a device it blocks Serial's built-in support for that device, forcing Serial to use the kernel driver. Therefore, a problematic or outdated kernel driver can affect your experience using Serial. To determine which driver is being used to access your device, see How can I tell which driver is being used to access a device? .
There is a vendor supplied driver for this device that is known to be unstable and can cause kernel panics and data loss. If you have this driver installed on your computer you may be presented with a warning. We strongly recommend removing this driver completely if present- see How to Remove a Kernel Driver .
Apple began shipping their own driver, "AppleUSBPLCOM", for some Prolific devices with macOS 10.14 (Mojave). If you're running 10.14 or later, and you experience problems with the device, the only option available is to disable the Apple driver - see How to Disable a Kernel Driver .