[Python] Python pefile Write failure

Fails on machine 1 but not on other machine.s The files are all hosted on machine 1 on a shared drive.

import sys
import pefile

pe = pefile.PE(sys.argv[1])
pe.write (sys.argv[1])
print "Finished!"


It fails on machine 1 with

pe.write (sys.argv[1])
File "n:\Python27\pefile.py", line 2155, in write
f = file(filename, 'wb+')
IOError: [Errno 22] invalid mode ('wb+') or filename: 'notepad.exe'


(excerpt form pefile

f = file(filename, 'wb+')
f.write(new_file_data)
f.close()


)

(but this works fine

f = file(sys.argv[1], 'wb+')
f.write("Hello World")
f.close()


)

Admitted this may not be a Python issue, I'm a bit stumped. The host machine is Windows Server 2016, client machines are Win 8 and Win 10 pro. I've tried a few different exes.

Edit - I retargetted this at Python 3.10 with the same result, except the error is slightly different

File "n:\python310\lib\site-packages\pefile.py", line 3325, in write
f = open(filename, "wb+")
OSError: [Errno 22] Invalid argument: 'notepad.exe'

Continue reading...