title: IndexError: list index out of range when save model in tensorflow
body: <p>Can anyone help me? i use tensorflow to train LSTM network. The training run well but when i want to save the model, i get error below.</p>
  
  <pre><code>Step 1, Minibatch Loss= 0.0146, Training Accuracy= 1.000
  Step 1, Minibatch Loss= 0.0129, Training Accuracy= 1.000
  Optimization Finished!
  Traceback (most recent call last):
    File ".\lstm.py", line 169, in &lt;module&gt;
      save_path = saver.save(sess, "modelslstm/" + str(time.strftime("%d-%m-%Y-%H-%M-%S")) + ".ckpt")
    File "C:\Python35\lib\site-packages\tensorflow\python\client\session.py", line 1314, in __exit__
      self._default_graph_context_manager.__exit__(exec_type, exec_value, exec_tb)
    File "C:\Python35\lib\contextlib.py", line 66, in __exit__
      next(self.gen)
    File "C:\Python35\lib\site-packages\tensorflow\python\framework\ops.py", line 3815, in get_controller
      if self.stack[-1] is not default:
  IndexError: list index out of range
  </code></pre>
  
  <p>My Code : </p>
  
  <pre><code>with tf.Session() as sess:
      os.environ['TF_CPP_MIN_LOG_LEVEL'] = '2'
      # from tensorflow.examples.tutorials.mnist import input_data
      # mnist = input_data.read_data_sets("/tmp/data/", one_hot=True)
      # a,b = mnist.train.next_batch(5)
      # print(b)
      # Run the initializer
      sess.run(init)
      saver = tf.train.Saver()
      merged_summary_op = tf.summary.merge_all()
      writer = tf.summary.FileWriter("trainlstm", sess.graph)
      #print(str(data.train.num_examples))
      for step in range(1, training_steps+1):
          for batch_i in range(data.train.num_examples // batch_size):
              batch_x, batch_y,name = data.train.next_batch(batch_size)
              #hasil,cost = encode(batch_x[0][0],"models/25-09-2017-15-25-54.ckpt")
              temp = []
              for batchi in range(batch_size):
                  temp2 = []
                  for ti in range(timesteps):
                      hasil,cost = encode(batch_x[batchi][ti],"models/25-09-2017-15-25-54.ckpt")
                      hasil = np.reshape(hasil,[num_input])
                      temp2.append(hasil.copy())
                  temp.append(temp2.copy())
              batch_x = temp
              # Reshape data to get 28 seq of 28 elements
              #batch_x = batch_x.reshape((batch_size, timesteps, num_input))
              #dlib.hit_enter_to_continue()
              # Run optimization op (backprop)
              sess.run(train_op, feed_dict={X: batch_x, Y: batch_y})
              # Calculate batch loss and accuracy
              loss, acc = sess.run([loss_op, accuracy], feed_dict={X: batch_x,
                                                                   Y: batch_y})
              print("Step " + str(step) + ", Minibatch Loss= " + \
                    "{:.4f}".format(loss) + ", Training Accuracy= " + \
                    "{:.3f}".format(acc))
              f.write("Step " + str(step) + ", Minibatch Loss= " + \
                    "{:.4f}".format(loss) + ", Training Accuracy= " + \
                    "{:.3f}".format(acc)+"\n")
  
      print("Optimization Finished!")
      save_path = saver.save(sess, "modelslstm/" + str(time.strftime("%d-%m-%Y-%H-%M-%S")) + ".ckpt")
  f.close()
  </code></pre>
  
  <p>i added tf.reset_default_graph() but it doesn't work.
  please help me to solve my problem.
  Thanks!</p>