What to do when the terminal displays "Sorry, could not find a PTY"? (Mac OSx)

Question

I'm connecting an android device to an FTDI, which is connected to my Mac. On my android device I'm using FTDI AOA HyperTerm. I can send chars without any problem to my mac using this program: https://www.decisivetactics.com/products/serial/. As you can see I can only use it for 7 days, so I want to use my Terminal instead. When I run this command:

screen /dev/tty.usbserial 9600

I get a blank screen with two messages, the second one being "Sorry, could not find a PTY".

What should I do to fix this?

EDIT: when I closed the Serial program, it worked on my Terminal. However, when I restart my Terminal it gives the same message. I open Serial, select my USB device, close serial and use my Terminal. Why is this?

Answer 1

I know this is old but I found the same problem today with my Raspberry PI and a PI UART card attached. I found that this error occurred when I opened up a screen session but didn't close it completely. I was able to fix by going to Activity Monitor and terminating any "screen" processes.