title: keras unable to call model.predict_classes for multiple times
body: <pre><code>def predictOne(imgPath):
  
      model = load_model("withImageMagic.h5")
      image = read_image(imgPath)
      test_sample = preprocess(image)
      predicted_class = model.predict_classes(([test_sample]))
      return predicted_class
  </code></pre>
  
  <p>I have already trained a model. In this function, I load my model, read a new image, do some preprocessing and finally predict its label. </p>
  
  <p>When I run my main.py file, this function is called and everything goes smoothly. However, after a couple of seconds, this function will be called again with another image and I get this error:</p>
  
  <blockquote>
  <pre><code>'Cannot interpret feed_dict key as Tensor: ' + e.args[0])
  </code></pre>
    
    <p>TypeError: Cannot interpret feed_dict key as Tensor: Tensor Tensor("Placeholder:0", shape=(5, 5, 1, 32), dtype=float32) is not an element of this graph.</p>
  </blockquote>
  
  <p>It's very strange that the function only works the first time. I tested multiple images and got the same behavior.</p>
  
  <p>Windows 10 - tensorflow-gpu with keras</p>