title: Cannot connect to X server GOOGLE COLAB
body: <p>I am trying to make a prediction using <strong>Tensorflow Object Detection API</strong> on <strong><em>Google COLAB</em></strong>. Already I successfully completed the training process and  <strong>Export Inference Graph</strong> task.</p>
  
  <p>But Problem is when I am going to make a new prediction it's throwing some error log.</p>
  
  <blockquote>
    <p>cannot connect to X server</p>
  </blockquote>
  
  <p>Now I am unable to make a new prediction. Some portion of my error log: </p>
  
  <pre><code>totalMemory: 11.17GiB freeMemory: 6.65GiB
  2019-02-07 15:08:38.398219: I tensorflow/core/common_runtime/gpu/gpu_device.cc:1512] Adding visible gpu devices: 0
  2019-02-07 15:08:38.745889: I tensorflow/core/common_runtime/gpu/gpu_device.cc:984] Device interconnect StreamExecutor with strength 1 edge matrix:
  2019-02-07 15:08:38.745955: I tensorflow/core/common_runtime/gpu/gpu_device.cc:990]      0 
  2019-02-07 15:08:38.745975: I 
  tensorflow/core/common_runtime/gpu/gpu_device.cc:1003] 0:   N
  2019-02-07 15:08:38.746201: W 
  tensorflow/core/common_runtime/gpu/gpu_bfc_allocator.cc:42] Overriding allow_growth setting because the TF_FORCE_GPU_ALLOW_GROWTH environment variable is set. Original config value was 0.
  2019-02-07 15:08:38.746259: I 
  tensorflow/core/common_runtime/gpu/gpu_device.cc:1115] Created TensorFlow device (/job:localhost/replica:0/task:0/device:GPU:0 with 6426 MB memory) -&gt; physical GPU (device: 0, name: Tesla K80, pci bus id: 0000:00:04.0, compute capability: 3.7)
  2019-02-07 15:08:39.683618: W ./tensorflow/core/grappler/optimizers/graph_optimizer_stage.h:241] Failed to run optimizer ArithmeticOptimizer, stage RemoveStackStridedSliceSameAxis node Preprocessor/map/while/ResizeToRange/strided_slice_3. Error: Pack node (Preprocessor/map/while/ResizeToRange/stack_2) axis attribute is out of bounds: 0
  2019-02-07 15:08:40.360560: W ./tensorflow/core/grappler/optimizers/graph_optimizer_stage.h:241] Failed to run optimizer ArithmeticOptimizer, stage RemoveStackStridedSliceSameAxis node Preprocessor/map/while/ResizeToRange/strided_slice_3. Error: Pack node (Preprocessor/map/while/ResizeToRange/stack_2) axis attribute is out of bounds: 0
  2019-02-07 15:08:40.646093: I tensorflow/stream_executor/dso_loader.cc:152] successfully opened CUDA library libcublas.so.10.0 locally
  : cannot connect to X server 
  </code></pre>
  
  <p>How can I figure out the reason for this problem?</p>