“Windows Error: provider DLL failed to initialize

Question

I have a user of a frozen wxpython app that gets the appended screenshot.

The error message is "Windows Error: provider DLL failed to initialize correctly"

A screenshot taken from a paused video is the only way I could get this error message from them because the whole thing disappears instantly (including this DOS window created to capture stderr, where this message is appearing). IE python is dieing before it even really gets going.

The traceback points to my code at controller.py line 14.

This line is

import cgi

For some reason, it seems that cgi is calling random during import (why would that be?) and for some reason this is failing for some DLL reason.

Any clues?

Note 1: this app works fine for hundreds of other Windows and Mac users. So it's as if I'm not supplying something that is not on only this user's machine for some reason.

Note 2: the executable is created using bbfreeze, with the following config:

 f = Freezer(distdir = distdir,
            includes = ['wx.lib.pubsub.core.kwargs.*',
                        'wx.lib.pubsub.core.*',
                        'dbhash',
                        'platform']
            )

I'm not sure what else I'd put in here. 'cgi'? 'random'?

Answer 1

This seems to occur somewhere inside os.urandom and is probably caused by some missing or incorrect environment variables. In particular it happens if the environment is too long.

• If you are starting Python from a shell, open a new shell and try again. If the problem persists, check if there are unusually many environment variables
• If you are starting Python from another process, check if the proces environment is set up correctly. I found that this is often not the case for processes run by Apache's CGI module.

if you are starting Python as a CGI process, then you may want to consider better alternatives, such as mod_wsgi.

Answer 2

For me, the exact error message was:

WindowsError: [Error -2146893795] Provider DLL failed to initialize correctly

with a trace such as:

  File "C:\Dev\Python\python-2.7.11\lib\tempfile.py", line 35, in <module>
    from random import Random as _Random
  File "C:\Dev\Python\python-2.7.11\lib\random.py", line 885, in <module>
    _inst = Random()
  File "C:\Dev\Python\python-2.7.11\lib\random.py", line 97, in __init__
    self.seed(x)
  File "C:\Dev\Python\python-2.7.11\lib\random.py", line 113, in seed
    a = long(_hexlify(_urandom(2500)), 16)
WindowsError: [Error -2146893795] Provider DLL failed to initialize correctly

And what solved it for me was a comment from http://bugs.python.org/issue1384175 (http://bugs.python.org/msg248947), saying the following:

This happened at a call to `os.urandom` for me.
This was in a subprocess.

The bug for me was that I called `_subprocess.CreateProcess` 
with an `env_mapper = {'foo': 'bar'}`. The fix:

    env_mapper = os.environ.copy()
    env_mapper.update({'foo': 'bar'})

Answer 3

I think the minimal solution is to include the SYSTEMROOT environment variable in the Python subprocess.

I have seen the problem when trying to load os.urandom:

self._authkey = AuthenticationString(os.urandom(32)) WindowsError: [Error -2146893795] Provider DLL failed to initialize correctly

It turns out that the _PyOS_URandom on Windows relies on the SYSTEMROOT environment to be set. See: http://bugs.python.org/issue1384175#msg248951 for a detailed explaination