Ah, that is a good idea, I am going to do that! Thanks again David!

Dang, I thought that I might have been on to something lol. I am going to have to do some more investigating it seems. :/

Also, thank you very much for your time David! I greatly appreciate it.

Hello! Thank you very much for your reply! Sorry that it took me so long to respond, I just had some time to sit back down at my computer!

I added a delay object in between the loadbang and the connect localhost 9001 message, and I varied the delay time from about 1 second to 5 seconds without any success. The file that I am testing is this one: osc_test_delay.pd.
I still get similar behavior, however, the error message
error: udpsend socket: Either the application has not called WSAStartup, or WSAStartup failed. (10093)
is just delayed by the amount of delay time.

I think what is happening is that, when pd's gui is started, it must be calling WSAStartup since 'pd-gui' has to make a connection to 'pd' on localhost 5400 (I discovered this by switching pd's console debug print level from 2 to 3). However, when pd's gui is not used, WSAStartup is not being called, and thus the socket connections cannot be made.

I am attempting to run this simple patch: osc_test.pd on my Windows 10 computer, headless, using pd 0.48-1 along with the mrpeach external. Using command prompt, I go to the directory that contains this patch, and then enter the command "pd -nogui osc_test.pd". When I do this, I get

error: udpreceive: socket: Either the application has not called WSAStartup, or WSAStartup failed. (10093)
verbose(4): ... you might be able to track this down from the Find menu.
error: udpsend socket: Either the application has not called WSAStartup, or WSAStartup failed. (10093)
error: udpsend: not connected

However, when I instead enter the command "pd osc_test.pd" (with the GUI) it is able to run properly. By run properly, I mean that

udpsend: connecting to port 9001
print: /test 20 30 40

is printed in the pd terminal window, which is the expected behavior.

I am looking for assistance in determining how to run this patch headless. It must be the case that "pd osc_test.pd" calls WSAStartup, but I am not sure why "pd -nogui osc_test.pd" does not …? Any help would be greatly appreciated!