On Windows, running “import tensorflow” generates No module named “_pywrap_tensorflow” error

Question

On Windows, TensorFlow reports either or both of the following errors after executing an import tensorflow statement:

• No module named \"_pyw

Answer 1

Ran into the same problem (in 2019/09/09) while investigating [SO]: Error while training using the estimator API in tensorflow.

Setup:

• Win 10 x64
• Python 3.7.3 (x64)
• TensorFlow-GPU 1.13.1 ([TensorFlow]: Install TensorFlow with pip)

Error:

[cfati@CFATI-5510-0:e:\Work\Dev\StackOverflow\q057588589]> "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\Scripts\python.exe" -c "import tensorflow as tf"
Traceback (most recent call last):
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\python\pywrap_tensorflow.py", line 58, in 
    from tensorflow.python.pywrap_tensorflow_internal import *
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\python\pywrap_tensorflow_internal.py", line 28, in 
    _pywrap_tensorflow_internal = swig_import_helper()
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\python\pywrap_tensorflow_internal.py", line 24, in swig_import_helper
    _mod = imp.load_module('_pywrap_tensorflow_internal', fp, pathname, description)
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\imp.py", line 242, in load_module
    return load_dynamic(name, filename, file)
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\imp.py", line 342, in load_dynamic
    return _load(spec)
ImportError: DLL load failed: The specified module could not be found.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "", line 1, in 
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\__init__.py", line 24, in 
    from tensorflow.python import pywrap_tensorflow  # pylint: disable=unused-import
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\python\__init__.py", line 49, in 
    from tensorflow.python import pywrap_tensorflow
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\python\pywrap_tensorflow.py", line 74, in 
    raise ImportError(msg)
ImportError: Traceback (most recent call last):
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\python\pywrap_tensorflow.py", line 58, in 
    from tensorflow.python.pywrap_tensorflow_internal import *
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\python\pywrap_tensorflow_internal.py", line 28, in 
    _pywrap_tensorflow_internal = swig_import_helper()
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\python\pywrap_tensorflow_internal.py", line 24, in swig_import_helper
    _mod = imp.load_module('_pywrap_tensorflow_internal', fp, pathname, description)
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\imp.py", line 242, in load_module
    return load_dynamic(name, filename, file)
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\imp.py", line 342, in load_dynamic
    return _load(spec)
ImportError: DLL load failed: The specified module could not be found.


Failed to load the native TensorFlow runtime.

See https://www.tensorflow.org/install/errors

for some common reasons and solutions.  Include the entire stack trace
above this error message when asking for help.

Looking at the "faulty" module (thanks to Dependency Walker), it turns out that it's not itself that's missing, but some of its dependencies (the cu*_100.dll files).

Check [SO]: Python Ctypes - loading dll throws OSError: [WinError 193] %1 is not a valid Win32 application (@CristiFati's answer) (the Conclusions section at the end) for more details on this kind of errors.
I had an older CUDA Toolkit version (8), and as a consequence, the cu*_80.dll files.

Upgrading to TensorFlow-GPU 1.14.0 ("e:\Work\Dev\VEnvs\py_064_03.07.03_test0\Scripts\python.exe" -m pip install --upgrade tensorflow-gpu), made the error a bit clearer (and also shorter):

[cfati@CFATI-5510-0:e:\Work\Dev\StackOverflow\q057588589]> "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\Scripts\python.exe" -c "import tensorflow as tf"
Traceback (most recent call last):
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\python\platform\self_check.py", line 75, in preload_check
    ctypes.WinDLL(build_info.cudart_dll_name)
  File "c:\install\x64\python\python\03.07.03\Lib\ctypes\__init__.py", line 356, in __init__
    self._handle = _dlopen(self._name, mode)
OSError: [WinError 126] The specified module could not be found

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "", line 1, in 
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\__init__.py", line 28, in 
    from tensorflow.python import pywrap_tensorflow  # pylint: disable=unused-import
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\python\__init__.py", line 49, in 
    from tensorflow.python import pywrap_tensorflow
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\python\pywrap_tensorflow.py", line 30, in 
    self_check.preload_check()
  File "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\lib\site-packages\tensorflow\python\platform\self_check.py", line 82, in preload_check
    % (build_info.cudart_dll_name, build_info.cuda_version_number))
ImportError: Could not find 'cudart64_100.dll'. TensorFlow requires that this DLL be installed in a directory that is named in your %PATH% environment variable. Download and install CUDA 10.0 from this URL: https://developer.nvidia.com/cuda-90-download-archive

Steps:

• Uninstall any CUDA Toolkit version (optional)
• Install [nVidia.Developer]: CUDA Toolkit 10.0 Archive
  • Make sure to install v10.0 (that this TensorFlow-GPU version was built against). I installed v10.1 (which was the latest, and also the recommended version at the answer time), and the .dll names didn't match (cu*_101.dll). Since I didn't want to install v10.0, I created some symlinks (with the "correct" names) to the existing files, and it worked. But bear in mind that this is unsupported!!! You may experience funny behavior (including crashes). This is a (lame) workaround (gainarie)
  • Additionally, a compatible (meaning that it's for a specific CUDA Toolkit version) cuDNN version ([nVidia.Developer]: cuDNN Archive) is required. In order to access the download URL, nVidia membership is required

After the above steps, and also setting the correct paths, it worked:

[cfati@CFATI-5510-0:e:\Work\Dev\StackOverflow\q057588589]> set PATH=%PATH%;%CUDA_PATH%\bin;f:\Install\x64\NVidia\GPU Computing Toolkit\cuDNN\7.6\bin

[cfati@CFATI-5510-0:e:\Work\Dev\StackOverflow\q057588589]> "e:\Work\Dev\VEnvs\py_064_03.07.03_test0\Scripts\python.exe" -c "import tensorflow;print(\"Success!!!\")"
Success!!!