Unable to open serial port using simply python script on macOS Catalina: [Errno 16] Resource is busy
I had the same problem, serial port resource busy and could not see which process used it.
I found this thread here: https://forums.developer.apple.com/thread/124414
They recommend installing the latest version of the FTDI driver, 2.4.2, found here: https://www.ftdichip.com/Drivers/VCP.htm
That did the trick.
Cheers
This doesn't work with Catalina. It throws error as following when tried to install.
/Library/Extensions/FTDIUSBSerialDriver.kext failed to load - (libkern/kext) not loadable (reason unspecified); check the system/kernel logs for errors or try kextutil(8)
sudo dmesg
Notice - new kext com.apple.driver.usb.AppleUSBHostPlatformProperties, v1.2 matches prelinked kext but can't determine if executables are the same (no UUIDs).
UPDATE from FTDI
Apple are moving from what are called Kernel Extentions (.kexts) to what are called Driver Extensions (.dexts) for the implementation of drivers starting in macOS Catalina (10.15). Currently .kexts are still supported in macOS Catalina, however after the beta release they issued an update which stopped our driver from loading. This update required our driver (FTDIUSBSerialDriver.kext) to be re-signed and notarized, we completed this process with an updated Apple Developer ID (as they lapse every two years). Unfortunately when Apple issued our new Developer ID to re-sign and notarize the driver package they did so without the .kext support option enabled (as .kexts are being deprecated it is no longer automatically included). This is why there is a code signature issue with our driver, currently we are waiting on Apple issuing us with the correct Developer ID to be able to sign .kexts for macOS Catalina.
As such our current VCP driver available on the website has a signature issue and wont load. However if the device you are using implements a default FTDI VID/PID combination it should be picked up by the inbuilt AppleUSBFTDI.dext driver and present accordingly in the ‘/dev’ folder on your system in the following form:
/dev/cu.usbserial-xxxxxxxx
/dev/tty.usbserial-xxxxxxxx
My FTDI module has default PID VID but still doesn't work. Apple needs to check. 