How to successfully implement Multiprocessing Lock?

Question

I have been following the example synchronization-between-processes from the multiprocessing document. The script is as follows:

from multiprocessing import Process, Lock

def f(l, i):
    l.acquire()
    try:
        print('hello world', i)
    finally:
        l.release()

if __name__ == '__main__':
    lock = Lock()

    for num in range(10):
        Process(target=f, args=(lock, num)).start()

When running this on virtual studio code, I get the following error:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/Users/usr/opt/anaconda3/lib/python3.8/multiprocessing/spawn.py", line 116, in spawn_main
    exitcode = _main(fd, parent_sentinel)
  File "/Users/usr/opt/anaconda3/lib/python3.8/multiprocessing/spawn.py", line 126, in _main
    self = reduction.pickle.load(from_parent)
  File "/Users/usr/opt/anaconda3/lib/python3.8/multiprocessing/synchronize.py", line 110, in __setstate__
    self._semlock = _multiprocessing.SemLock._rebuild(*state)

However, when I run the threading version, I get:

#from multiprocessing import Process, Lock
from threading import Thread, Lock

def f(l, i):
    l.acquire()
    try:
        print('hello world', i)
    finally:
        l.release()

if __name__ == '__main__':
    lock = Lock()

    for num in range(10):
        Thread(target=f, args=(lock, num)).start()

#
hello world 0
hello world 1
hello world 2
hello world 3
hello world 4
hello world 5
hello world 6
hello world 7
hello world 8
hello world 9

Why am I getting an error from the first example?