title: How to fix training error launch:90 in YOLOX?
body: <pre><code>!python tools/train.py -f exps/example/yolox_voc/yolox_voc_s.py -d 1 -b 16 --fp16  -c /content/yolox_s.pth
  </code></pre>
  <pre><code>2022-03-29 19:24:57 | INFO     | apex.amp.frontend:356 - enabled                : True
  2022-03-29 19:24:57 | INFO     | apex.amp.frontend:356 - opt_level              : O1
  2022-03-29 19:24:57 | INFO     | apex.amp.frontend:356 - cast_model_type        : None
  2022-03-29 19:24:57 | INFO     | apex.amp.frontend:356 - patch_torch_functions  : True
  2022-03-29 19:24:57 | INFO     | apex.amp.frontend:356 - keep_batchnorm_fp32    : None
  2022-03-29 19:24:57 | INFO     | apex.amp.frontend:356 - master_weights         : None
  2022-03-29 19:24:57 | INFO     | apex.amp.frontend:356 - loss_scale             : dynamic
  2022-03-29 19:24:57 | INFO     | yolox.core.trainer:297 - loading checkpoint for fine tuning
  2022-03-29 19:24:57 | WARNING  | yolox.utils.checkpoint:27 - Shape of head.cls_preds.0.weight in checkpoint is torch.Size([80, 128, 1, 1]), while shape of head.cls_preds.0.weight in model is torch.Size([3, 128, 1, 1]).
  2022-03-29 19:24:57 | WARNING  | yolox.utils.checkpoint:27 - Shape of head.cls_preds.0.bias in checkpoint is torch.Size([80]), while shape of head.cls_preds.0.bias in model is torch.Size([3]).
  2022-03-29 19:24:57 | WARNING  | yolox.utils.checkpoint:27 - Shape of head.cls_preds.1.weight in checkpoint is torch.Size([80, 128, 1, 1]), while shape of head.cls_preds.1.weight in model is torch.Size([3, 128, 1, 1]).
  2022-03-29 19:24:57 | WARNING  | yolox.utils.checkpoint:27 - Shape of head.cls_preds.1.bias in checkpoint is torch.Size([80]), while shape of head.cls_preds.1.bias in model is torch.Size([3]).
  2022-03-29 19:24:57 | WARNING  | yolox.utils.checkpoint:27 - Shape of head.cls_preds.2.weight in checkpoint is torch.Size([80, 128, 1, 1]), while shape of head.cls_preds.2.weight in model is torch.Size([3, 128, 1, 1]).
  2022-03-29 19:24:57 | WARNING  | yolox.utils.checkpoint:27 - Shape of head.cls_preds.2.bias in checkpoint is torch.Size([80]), while shape of head.cls_preds.2.bias in model is torch.Size([3]).
  2022-03-29 19:24:57 | ERROR    | yolox.core.launch:90 - An error has been caught in function 'launch', process 'MainProcess' (1549), thread 'MainThread' (140243385931648):
  Traceback (most recent call last):
  
    File &quot;tools/train.py&quot;, line 125, in &lt;module&gt;
      args=(exp, args),
            │    └ Namespace(batch_size=16, ckpt='/content/yolox_s.pth', devices=1, dist_backend='nccl', dist_url=None, exp_file='exps/example/y...
            └ ╒══════════════════╤═════════════════════════════════════════════════════════════════════════════════════════════════════════...
  
  &gt; File &quot;/content/apex/YOLOX/yolox/core/launch.py&quot;, line 90, in launch
      main_func(*args)
      │          └ (╒══════════════════╤════════════════════════════════════════════════════════════════════════════════════════════════════════...
      └ &lt;function main at 0x7f8cf10d3e60&gt;
  
    File &quot;tools/train.py&quot;, line 104, in main
      trainer.train()
      │       └ &lt;function Trainer.train at 0x7f8bf2234d40&gt;
      └ &lt;yolox.core.trainer.Trainer object at 0x7f8bec4a7a90&gt;
  
    File &quot;/content/apex/YOLOX/yolox/core/trainer.py&quot;, line 69, in train
      self.before_train()
      │    └ &lt;function Trainer.before_train at 0x7f8bec969710&gt;
      └ &lt;yolox.core.trainer.Trainer object at 0x7f8bec4a7a90&gt;
  
    File &quot;/content/apex/YOLOX/yolox/core/trainer.py&quot;, line 150, in before_train
      no_aug=self.no_aug,
             │    └ False
             └ &lt;yolox.core.trainer.Trainer object at 0x7f8bec4a7a90&gt;
  
    File &quot;exps/example/yolox_voc/yolox_voc_s.py&quot;, line 36, in get_data_loader
      max_labels=50,
  
    File &quot;/content/apex/YOLOX/yolox/data/datasets/voc.py&quot;, line 115, in __init__
      os.path.join(rootpath, &quot;ImageSets&quot;, &quot;Main&quot;, name + &quot;.txt&quot;)
      │  │    │    │                              └ 'trainval'
      │  │    │    └ '/content/apex/YOLOX/datasets/VOCdevkit/VOC2007'
      │  │    └ &lt;function join at 0x7f8cf31177a0&gt;
      │  └ &lt;module 'posixpath' from '/usr/lib/python3.7/posixpath.py'&gt;
      └ &lt;module 'os' from '/usr/lib/python3.7/os.py'&gt;
  
  FileNotFoundError: [Errno 2] No such file or directory: '/content/apex/YOLOX/datasets/VOCdevkit/VOC2007/ImageSets/Main/trainval.txt'
  </code></pre>
  <p>The file is present in <code>/content/YOLOX/datasets/VOCdevkit/VOC2007/ImageSets/Main/trainval.txt</code>
  But not in <code>/content/apex/YOLOX/datasets/VOCdevkit/VOC2007/ImageSets/Main/trainval.txt</code></p>
  <p>How do I fix this?</p>