Prolific PL-2303 Driver – Vista x64

I purchased a USB to RS232 Serial cable so I could hook up my GPS unit to my laptop and found out that installing the driver on Vista 64 was problematic. 

Disabling driver signing verification with the following command at an elevated prompt, followed by a reboot, enabled me to install the driver.


Download the prolific XP 64 bit driver (installs on Vista 64 after disabling driver signing verification) from:


18 thoughts on “Prolific PL-2303 Driver – Vista x64

  1. http://

    I have tried this, too. One time, I got the converter working, but now, the driver refuses to install with a “Code 39” error. What could that be?

  2. http://

    I also got a code 39 error, plus a popup telling me that the drivers weren’t signed (I know) and that this version of Windows requires signed drivers… I had disabled driver signing verification. I’m using Vista x64 business edition so will look to see if that has additional requirements for signed drivers.

  3. http://

    i had the same problem till i decided to use vista updates for other non-windows driver. they had it. before that i was considering going to a 1-legged midget butt kicking contest after visiting all them “free sites” that charge 9.99 and then another 12 bucks for shipping.

  4. http://

    Vista 64 Pro (French edition, translation may be approximative) : seems to me that the ‘code 39’ syndrom is the reason Vista 64 reports when it refuses to load an installed yet unsigned driver. Got this after initial install of the Prolific XP64 drivers, selecting advanced Vista boot options ‘disable driver signature verification’ made the very same driver operational, next boot without the option back to ‘code 39’ again. Boot option is boring since must be specified on each startup, the magic command line is intended to make the option permanent, I guess, given what BCDEDIT /? seems to tell us.

  5. http://

    Randy, I am very interested in finding out where you downloaded drivers through Vista updates cause it’s not working for me and can’t seem to find it anywhere on microsoft site. I am using Vista x64.


  6. http://

    Hi all!

    Unfortunately (or not, it depends…) you cannot disable the kernel patchguard system in Vista x64: you can’t install an unsigned driver and there’s nothing you can do about it.

    So I think we have to look for another usb-serial converter, maybe in the Windows Vista HCL!

    I’m going to try to use Vmware Workstation and a Xp vm as a workaround.


  7. nattygreg

    Next time create an administrator account and take ownership of the system administrator account, so the next time you install a driver the system will not protect itself but trust you as the system administrator and will load the driver, appl with no problem

  8. http://

    QUOTE(Red Mist @ Aug 27 2007, 08:59 AM) *
    Hey , i had the same problem with a gps reciever i have, there was no prolific drivers for the

    prolific usb to serial adapter for vista 32 or 64, What i did was use the xp64 or xp32 drivers

    depending on which version of vista you are running.

    Dunno if you’ve tried this but restart vista then at the post screen,press F8 to get to the vista

    load option’s, select dissable driver signing, Vista will now load & you can install your XP 64

    drivers in your vitsa 64…..This may or may not work, but it did work for me & my gps works now on

    my vista laptop.

    Hi Red Mist,

    I have diabled the driver signing permanent, and I have installed some unsigned driver without a

    problem. But with the prolific XP64 driver I have the problem. VISTA64 isn’t accepting the driver

    nerves.gif and I don’t know why.


    After installing the driver VISTA gives an error message, that the driver isn’t sign, but now I

    have seen in the device manager that the driver is loaded. And it works thmbup.gif

  9. http://

    after quite a bit of tinkering, this did not work for me on Vista Ultimate x64

    i had several failed installations prior to this and this was causing a problem, COM19 sound familiar? kept getting “service name already in use” error … going forward, I will use a laptop with a 9-pin serial connector, BOO!

  10. jpo

    Is anything more annoying than devices that can’t be bothered to implement an actual USB interface, and instead insist on using decade-old serial interfaces and requiring buggy, unsupported COM->USB drivers? GPS units from a variety of manufacturers seem particularly prone to this.

  11. Steve

    Actually, the annoying thing isn’t devices not implementing a USB interface, it is Microsoft not supporting a decade old USB standard (CDC/ACM).

    These GPS devices and many other virtual serial implementations plug in and work immediately in other operating systems (Linux, MacOS X) with no drivers other than the system’s built in drivers. Windows simply has been broken for decades and can’t be bothered to fix things so vendors, customers, and hardware point fingers, reload operating sytems, etc.

    Direct your disgust to where it belongs… in Microsoft’s inability to support recognized standards. Better yet, vote for improvents by just using a different operating system. You will be pleasantly surprised.

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