Code 39 error when using CyUSB.sys in Vista 64-bit machine (code 52 in the case of Windows 7)

Question: Usage of CyUSB.sys in Vista 64-bit operating system gives Code 39 error (Code 52 in the case of Windows 7). What does this error mean?



CyUSB.sys downloaded through our website is an unsigned driver. Using it in 64-bit operating system without disabling driver signature enforcement is a possible reason for this behavior.

Following are the steps to disable driver signature enforcement in 64-bit operating system

1.       During boot-up press F8.

2.       In the list of options that appear select “Disable driver signature enforcement”.

Find KB article Why is CyUSB.sys not WHQL signed? for details on why a signed driver is not provided. Find Application note Windows Hardware Quality Lab signing procedure for details on driver signing procedure.

Note: In the case of Windows Vista 64-bit operating system the error message is “Windows cannot load the device driver for this hardware. The driver may be corrupted or missing. (Code 39)”

In the case of Windows 7 64-bit operating system it is "Windows cannot verify the digital signature for the drivers required for this device. A recent hardware or software change might have installed a file that is signed incorrectly or damaged, or that might be malicious software from an unknown source. (Code 52)".