Whenever startupinfo is called, python crashes on my Computer. I have added the file showing the error traceback. I have seen a few bug Reports related to startupinfo on Windows. Not sure what the issue is and I hope you can help me. 

I am running the python code via spyder. My apologies if this is not the forum for these Kind of questions.

The screenshot says "OSError: [WinError 87] Falscher Parameter" at Lib/subprocess.py:1178 which is this call:

                hp, ht, pid, tid = _winapi.CreateProcess(executable, args,
                                         # no special security
                                         None, None,
                                         int(not close_fds),
                                         creationflags,
                                         env,
                                         os.fspath(cwd) if cwd is not None else None,
                                         startupinfo)

According to the traceback, the call is:

subprocess.check_output([execStr,"-3",self.geofile,"-o",self.vtkFile])

Can you please dump these parameters? Are they all strings?

IMHO execStr, self.geofile or self.vtkFile is not a valid string and it's a bug in your code.

Context:

* bpo-34044
* commit 29be3bd3c9aed0190e60096a603120cacda82375
* Comments on the commit: https://github.com/python/cpython/commit/29be3bd3c9aed0190e60096a603120cacda82375#commitcomment-31855236

"Issue with execute_child in startupinfo"

I don't think that the issue is related to startupinfo at all, since you don't specify this parameter in your check_output() call. Python shows you "startupinfo)" in the traceback because the function call takes multiple lines in the source code.

This issue is not a crash: it's possible to catch the exception and continue the execution.

Thank you for the input Victor. I will need a little time to dig in the code and check the attributes. I am fairly new to python :)

You are right that the code doesn't crash. Just I cannot continue with the following steps. That is why I thought it crashed.

Hello Victor, 

a new version of the code has been released and I now get another error. I will mark the issue as resolved. Thank you for the quick response!

Ok, you're welcome ;-)

I've recently hit this problem (or one that has the same symptoms):

```
Traceback (most recent call last):
  File "migration.py", line 169, in <module>
    migrate()
  File "migration.py", line 80, in migrate
    rtc.acceptchangesintoworkspace(rtc.getchangeentriestoaccept(changeentries, history))
  File "c:\Users\GeoffAlexander\Documents\Nirvana\RTC2Git\git-repositories\rtc2git-migration-tool\rtcFunctions.py", line 310, in acceptchangesintoworkspace
    Commiter.addandcommit(changeEntry)
  File "c:\Users\GeoffAlexander\Documents\Nirvana\RTC2Git\git-repositories\rtc2git-migration-tool\gitFunctions.py", line 97, in addandcommit
    Commiter.handle_captitalization_filename_changes()
  File "c:\Users\GeoffAlexander\Documents\Nirvana\RTC2Git\git-repositories\rtc2git-migration-tool\gitFunctions.py", line 130, in handle_captitalization_filename_changes
    files = shell.getoutput("git ls-files")
  File "c:\Users\GeoffAlexander\Documents\Nirvana\RTC2Git\git-repositories\rtc2git-migration-tool\shell.py", line 33, in getoutput
    outputasbytestring = check_output(command, shell=True)
  File "C:\Users\GeoffAlexander\AppData\Local\Programs\Python\Python36\lib\subprocess.py", line 356, in check_output
    **kwargs).stdout
  File "C:\Users\GeoffAlexander\AppData\Local\Programs\Python\Python36\lib\subprocess.py", line 423, in run
    with Popen(*popenargs, **kwargs) as process:
  File "C:\Users\GeoffAlexander\AppData\Local\Programs\Python\Python36\lib\subprocess.py", line 729, in __init__
    restore_signals, start_new_session)
  File "C:\Users\GeoffAlexander\AppData\Local\Programs\Python\Python36\lib\subprocess.py", line 1017, in _execute_child
    startupinfo)
OSError: [WinError 87] The parameter is incorrect
```

I've tried Python 3.7.2 32-bit, 3.7.2 64-bit, and 3.6.8 64-bit on Windows 10.  The error occurs in a long running Python script after more than one and half hours.  The subprocess.check_output call at shell.py:33 is successfully called hundreds, probably thousands, of times before failing.

I see that the issue is reported as resolved.  But I'm not understanding what is meant by

```
a new version of the code has been released
```

I'm running the latest version of Python, Python 3.7.2, from https://www.python.org/downloads/windows/ (as well as the previous version 3.6.8).  Is there a later version of Python I can try?  Or do I need to get a newer version of the Python subprocess module?

I'm new to Python and wasn't sure if I should reopen this issue or create a new issue.  Please let me know if there any additional information I can collect to help debug this problem.

Here's the trace back I get from Python 3.7.2:

Traceback (most recent call last):
  File "migration.py", line 169, in <module>
    migrate()
  File "migration.py", line 80, in migrate
    rtc.acceptchangesintoworkspace(rtc.getchangeentriestoaccept(changeentries, history))
  File "c:\Users\GeoffAlexander\Documents\Nirvana\RTC2Git\git-repositories\rtc2git-migration-tool\rtcFunctions.py", line 310, in acceptchangesintoworkspace
    Commiter.addandcommit(changeEntry)
  File "c:\Users\GeoffAlexander\Documents\Nirvana\RTC2Git\git-repositories\rtc2git-migration-tool\gitFunctions.py", line 97, in addandcommit
    Commiter.handle_captitalization_filename_changes()
  File "c:\Users\GeoffAlexander\Documents\Nirvana\RTC2Git\git-repositories\rtc2git-migration-tool\gitFunctions.py", line 130, in handle_captitalization_filename_changes
    files = shell.getoutput("git ls-files")
  File "c:\Users\GeoffAlexander\Documents\Nirvana\RTC2Git\git-repositories\rtc2git-migration-tool\shell.py", line 33, in getoutput
    outputasbytestring = check_output(command, shell=True)
  File "C:\Users\GeoffAlexander\AppData\Local\Programs\Python\Python37-32\lib\subprocess.py", line 395, in check_output
    **kwargs).stdout
  File "C:\Users\GeoffAlexander\AppData\Local\Programs\Python\Python37-32\lib\subprocess.py", line 472, in run
    with Popen(*popenargs, **kwargs) as process:
  File "C:\Users\GeoffAlexander\AppData\Local\Programs\Python\Python37-32\lib\subprocess.py", line 775, in __init__
    restore_signals, start_new_session)
  File "C:\Users\GeoffAlexander\AppData\Local\Programs\Python\Python37-32\lib\subprocess.py", line 1178, in _execute_child
    startupinfo)
OSError: [WinError 87] The parameter is incorrect

Geoff, we probably need a new issue for this, but first, please report the value of len(os.getcwd()) in a case where check_output() fails. 

Prior to Windows 10, the working directory is limited to MAX_PATH - 2 (258) characters. (Windows uses the last two characters internally for a trailing backslash and a terminating null.) However, even with long-path support enabled in Windows 10, CreateProcessW retains the original WINAPI limit, which I assume is because the current implementation doesn't know whether the child supports long paths. If the inherited current directory exceeds this limit, CreateProcessW fails with ERROR_INVALID_PARAMETER (87).

> Geoff, we probably need a new issue for this,

Yes please, this issue is closed.

> Prior to Windows 10, the working directory is limited to MAX_PATH - 2 (258) characters. (...) CreateProcessW fails with ERROR_INVALID_PARAMETER (87).

Geoff: for your bug report, please dump len(os.getcwd()) as Eryk asked, but try also to dump all arguments passed to CreateProcess, or at least arguments passed to subprocess.

The [WinError 87] does seems to be caused by the current directory's name being too long.  The value of len(os.getcwd())is 260 when the exception occurs.  The failing call was subprocess.check_output("git ls-files", shell=True).  I've open Issue 36213 to track this problem.