OSError: [WinError 193] %1 is not a valid Win32 application

I am trying to call a Python file "hello.py" from within the python interpreter with subprocess. But I am unable to resolve this error. [Python 3.4.1].

import subprocess    
subprocess.call(['hello.py', 'htmlfilename.htm'])
Traceback (most recent call last):
  File "<pyshell#42>", line 1, in <module>
    subprocess.call(['hello.py', 'htmlfilename.htm'])
  File "C:\Python34\lib\subprocess.py", line 537, in call
    with Popen(*popenargs, **kwargs) as p:
  File "C:\Python34\lib\subprocess.py", line 858, in __init__
    restore_signals, start_new_session)
  File "C:\Python34\lib\subprocess.py", line 1111, in _execute_child
    startupinfo)
OSError: [WinError 193] %1 is not a valid Win32 application

Also is there any alternate way to "call a python script with arguments" other than using subprocess?

The error is pretty clear. The file hello.py is not an executable file. You need to specify the executable:

subprocess.call(['python.exe', 'hello.py', 'htmlfilename.htm'])

You'll need python.exe to be visible on the search path, or you could pass the full path to the executable file that is running the calling script:

import sys
subprocess.call([sys.executable, 'hello.py', 'htmlfilename.htm'])

Python installers usually register .py files with the system. If you run the shell explicitly, it works:

import subprocess
subprocess.call(['hello.py', 'htmlfilename.htm'], shell=True)
# --- or ----
subprocess.call('hello.py htmlfilename.htm', shell=True)

You can check your file associations on the command line with

C:\>assoc .py
.py=Python.File

C:\>ftype Python.File
Python.File="C:\Python27\python.exe" "%1" %*

I got the same error while I forgot to use shell=True in the subprocess.call.

subprocess.call('python modify_depth_images.py', shell=True)

Running External Command

To run an external command without interacting with it, such as one would do with os.system(), Use the call() function.

import subprocess

Simple command subprocess.call(['ls', '-1'], shell=True)

All above solution are logical and I think covers the root cause, but for me, none of the above worked. Hence putting it here as may be helpful for others.

My environment was messed up. As you can see from the traceback, there are two python environments involved here:

1. C:\Users\example\AppData\Roaming\Python\Python37
2. C:\Users\example\Anaconda3

I cleaned up the path and just deleted all the files from C:\Users\example\AppData\Roaming\Python\Python37.

Then it worked like the charm.

This link helped me to found the solution.