title: Check failed: mdb_status == 0 (2 vs. 0) No such file or directory
body: <p>I received the following error while I was training the data. I have tried all the solutions given on the internet and nothing seems to work for me. I have checked paths and size of the lmdb files are non-zero. But the problem still exists. I have no idea how to solve this issue.</p>
  
  <pre><code>pooling_
  I0411 12:42:53.114141 21769 layer_factory.hpp:77] Creating layer data
  I0411 12:42:53.114586 21769 net.cpp:91] Creating Layer data
  I0411 12:42:53.114604 21769 net.cpp:399] data -&gt; data
  I0411 12:42:53.114645 21769 net.cpp:399] data -&gt; label
  F0411 12:42:53.114650 21772 db_lmdb.hpp:14] Check failed: mdb_status == 0 (2 
  vs. 0) No such file or directory
  *** Check failure stack trace: ***
  I0411 12:42:53.114673 21769 data_transformer.cpp:25] Loading mean file from: 
  /home/Documents/Test/Images300/train_image_mean.binaryproto
  @ 0x7fa9436a3daa (unknown)
  @ 0x7fa9436a3ce4 (unknown)
  @ 0x7fa9436a36e6 (unknown)
  @ 0x7fa9436a6687 (unknown)
  @ 0x7fa943b0472e caffe::db::LMDB::Open()
  @ 0x7fa943afc644 caffe::DataReader::Body::InternalThreadEntry()
  @ 0x7fa940e46a4a (unknown)
  @ 0x7fa9406fe182 start_thread
  @ 0x7fa942a8a47d (unknown)
  @ (nil) (unknown)
  Aborted (core dumped)
  </code></pre>
  
  <p>Below is my file settings:</p>
  
  <pre><code>name: "GoogleNet"
  layer {
      name: "data"
      type: "Data"
      top: "data"
      top: "label"
      include {
          phase: TRAIN
      }
      transform_param {
          mirror: true
          crop_size: 224
          mean_file: "/home/Documents/Test/Images300/train_image_mean.binaryproto"
      }
      data_param {
          source: "/home/caffe/examples/zImageDetection/ImageDetection_train_lmdb"
          batch_size: 32
          backend: LMDB
      }
  }
  layer {
      name: "data"
      type: "Data"
      top: "data"
      top: "label"
      include {
          phase: TEST
      }
      transform_param {
          mirror: false
          crop_size: 224
          mean_file: "/home/Documents/Test/Image300/test_image_mean.binaryproto"
      }
      data_param {
          source: "/home/caffe/examples/zImageDetection/ImageDetection_val_lmdb"
          batch_size: 50
          backend: LMDB
      }
  }
  </code></pre>