windows上安装tensorflow时报错，“DLL load failed: 找不到指定的模块”的解决方式

最近打算开始研究一下机器学习，今天在windows上装tensorflow花了点功夫，其实前面的步骤不难，只要依次装好python3.5，numpy，tensorflow就行了，有一点要注意的是目前只有python3.5能装tensorflow，最新版的python3.6都不行。

装好tensorflow后，我建议大家不要直接用测试用例进行测试（如果没装好的话出现的错误一般都是：module ‘tensorflow’ has no attribute ‘constant’）。第一次测试时可以在python shell里面输入：

import tensorflow

如果没有报错，恭喜你，十有八九是装好了，这时可以再用简单的测试用例测试一下。但我估计没报错的话你也不会看到这篇博客了。。。

事实上，我第一次安装的时候出现了如下错误： 
Traceback (most recent call last): 
File “D:\Python\Python35\lib\site-packages\tensorflow\python\pywrap_tensorflow_internal.py”, line 18, in swig_import_helper 
return importlib.import_module(mname) 
File “D:\Python\Python35\lib\importlib__init__.py”, line 126, in import_module 
return _bootstrap._gcd_import(name[level:], package, level) 
File “frozen importlib._bootstrap”, line 986, in _gcd_import 
File “frozen importlib._bootstrap”, line 969, in _find_and_load 
File “frozen importlib._bootstrap”, line 958, in _find_and_load_unlocked 
File “frozen importlib._bootstrap”, line 666, in _load_unlocked 
File “frozen importlib._bootstrap”, line 577, in module_from_spec 
File “frozen importlib._bootstrap_external”, line 906, in create_module 
File “frozen importlib._bootstrap”, line 222, in _call_with_frames_removed 
ImportError: DLL load failed: 找不到指定的模块。

During handling of the above exception, another exception occurred:

Traceback (most recent call last): 
File “D:\Python\Python35\lib\site-packages\tensorflow\python\pywrap_tensorflow.py”, line 41, in module 
from tensorflow.python.pywrap_tensorflow_internal import * 
File “D:\Python\Python35\lib\site-packages\tensorflow\python\pywrap_tensorflow_internal.py”, line 21, in module 
_pywrap_tensorflow_internal = swig_import_helper() 
File “D:\Python\Python35\lib\site-packages\tensorflow\python\pywrap_tensorflow_internal.py”, line 20, in swig_import_helper 
return importlib.import_module(‘_pywrap_tensorflow_internal’) 
File “D:\Python\Python35\lib\importlib__init__.py”, line 126, in import_module 
return _bootstrap._gcd_import(name[level:], package, level) 
ImportError: No module named ‘_pywrap_tensorflow_internal’

During handling of the above exception, another exception occurred:

Traceback (most recent call last): 
File “pyshell#0”, line 1, in module 
import tensorflow 
File “D:\Python\Python35\lib\site-packages\tensorflow__init__.py”, line 24, in module 
from tensorflow.python import * 
File “D:\Python\Python35\lib\site-packages\tensorflow\python__init__.py”, line 51, in module 
from tensorflow.python import pywrap_tensorflow 
File “D:\Python\Python35\lib\site-packages\tensorflow\python\pywrap_tensorflow.py”, line 52, in module 
raise ImportError(msg) 
ImportError: Traceback (most recent call last): 
File “D:\Python\Python35\lib\site-packages\tensorflow\python\pywrap_tensorflow_internal.py”, line 18, in swig_import_helper 
return importlib.import_module(mname) 
File “D:\Python\Python35\lib\importlib__init__.py”, line 126, in import_module 
return _bootstrap._gcd_import(name[level:], package, level) 
File “frozen importlib._bootstrap”, line 986, in _gcd_import 
File “frozen importlib._bootstrap”, line 969, in _find_and_load 
File “frozen importlib._bootstrap”, line 958, in _find_and_load_unlocked 
File “frozen importlib._bootstrap”, line 666, in _load_unlocked 
File “frozen importlib._bootstrap”, line 577, in module_from_spec 
File “frozen importlib._bootstrap_external”, line 906, in create_module 
File “frozen importlib._bootstrap”, line 222, in _call_with_frames_removed 
ImportError: DLL load failed: 找不到指定的模块。

During handling of the above exception, another exception occurred:

Traceback (most recent call last): 
File “D:\Python\Python35\lib\site-packages\tensorflow\python\pywrap_tensorflow.py”, line 41, in module 
from tensorflow.python.pywrap_tensorflow_internal import * 
File “D:\Python\Python35\lib\site-packages\tensorflow\python\pywrap_tensorflow_internal.py”, line 21, in module 
_pywrap_tensorflow_internal = swig_import_helper() 
File “D:\Python\Python35\lib\site-packages\tensorflow\python\pywrap_tensorflow_internal.py”, line 20, in swig_import_helper 
return importlib.import_module(‘_pywrap_tensorflow_internal’) 
File “D:\Python\Python35\lib\importlib__init__.py”, line 126, in import_module 
return _bootstrap._gcd_import(name[level:], package, level) 
ImportError: No module named ‘_pywrap_tensorflow_internal’

Failed to load the native TensorFlow runtime.

See https://www.tensorflow.org/install/install_sources#common_installation_problems

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

之前在网上查安装方法时，大多数都说要装一个Anaconda，但我是直接装的python3.5，所以没装Anaconda，我相信问题不在这里。后来看到有人说装了visual studio2017解决了这个错误，我想不至于吧，装个tensorflow还要装个visual studio2017？事实上只是visual studio2017中刚好有运行tensorflow必须的运行时环境。所以，只要安装一下缺少的运行时环境就可以了，可以在如下网站中按照它的install instructions进行安装，非常简单，只要注意选对32位和64位的版本就行了。

https://www.microsoft.com/en-us/download/details.aspx?id=53587

装好后tensorflow就可以正常使用了~