diff --git a/CHANGELOG.md b/CHANGELOG.md
index d485ae6..a642b59 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ All notable changes to this project will be documented in this file.
 - Save checkpoint_0.pth (model before any training)
 - `SevenNetGraphDataset._file_to_graph_list` -> `SevenNetGraphDataset.file_to_graph_list`
 - Refactoring `SevenNetGraphDataset`, skips computing statistics if it is loaded, more detailed logging
+- Prefer use .get when accessing config dict
 ### Fixed
 - Fix error when loading `SevenNetGraphDataset` with other types of data (ex: extxyz) in one dataset
 
diff --git a/sevenn/error_recorder.py b/sevenn/error_recorder.py
index 96c342d..9c27bf6 100644
--- a/sevenn/error_recorder.py
+++ b/sevenn/error_recorder.py
@@ -331,16 +331,17 @@ def init_total_loss_metric(config, criteria):
 
     @staticmethod
     def from_config(config: dict):
-        loss_cls = loss_dict[config[KEY.LOSS].lower()]
-        try:
-            loss_param = config[KEY.LOSS_PARAM]
-        except KeyError:
-            loss_param = {}
+        loss_cls = loss_dict[config.get(KEY.LOSS, 'mse').lower()]
+        loss_param = config.get(KEY.LOSS_PARAM, {})
         criteria = loss_cls(**loss_param)
 
-        err_config = config[KEY.ERROR_RECORD]
+        err_config = config.get(KEY.ERROR_RECORD, False)
+        if not err_config:
+            raise ValueError(
+                'No error_record config found. Consider util.get_error_recorder'
+            )
         err_config_n = []
-        if not config[KEY.IS_TRAIN_STRESS]:
+        if not config.get(KEY.IS_TRAIN_STRESS, True):
             for err_type, metric_name in err_config:
                 if 'Stress' in err_type:
                     continue
diff --git a/sevenn/scripts/processing_epoch.py b/sevenn/scripts/processing_epoch.py
index aabcb27..d2987bf 100644
--- a/sevenn/scripts/processing_epoch.py
+++ b/sevenn/scripts/processing_epoch.py
@@ -32,8 +32,8 @@ def processing_epoch_v2(
     prefix = f'{os.path.abspath(working_dir)}/'
 
     total_epoch = total_epoch or config[KEY.EPOCH]
-    per_epoch = per_epoch or config[KEY.PER_EPOCH]
-    best_metric = best_metric or config[KEY.BEST_METRIC]
+    per_epoch = per_epoch or config.get(KEY.PER_EPOCH, 10)
+    best_metric = best_metric or config.get(KEY.BEST_METRIC, 'TotalLoss')
     recorder = error_recorder or ErrorRecorder.from_config(config)
     recorders = {k: deepcopy(recorder) for k in loaders}
 
diff --git a/sevenn/train/graph_dataset.py b/sevenn/train/graph_dataset.py
index 4f4d8ab..8ccd1b4 100644
--- a/sevenn/train/graph_dataset.py
+++ b/sevenn/train/graph_dataset.py
@@ -172,8 +172,24 @@ def __init__(
             processed_name += '.pt'
         self._processed_names = [
             processed_name,  # {root}/sevenn_data/{name}.pt
-            processed_name.replace('pt', 'yaml'),
+            processed_name.replace('.pt', '.yaml'),
         ]
+
+        root = root or './'
+        _pdir = os.path.join(root, 'sevenn_data')
+        _pt = os.path.join(_pdir, self._processed_names[0])
+        if not os.path.exists(_pt) and len(self._files) == 0:
+            raise ValueError((
+                f'{_pt} not found and no files to process. '
+                + 'If you copied only .pt file, please copy '
+                + 'whole sevenn_data dir without changing its name.'
+                + ' They all work together.'
+            ))
+
+        _yam = os.path.join(_pdir, self._processed_names[1])
+        if not os.path.exists(_yam) and len(self._files) == 0:
+            raise ValueError(f'{_yam} not found and no files to process')
+
         self.process_num_cores = process_num_cores
         self.process_kwargs = process_kwargs
 
diff --git a/sevenn/train/trainer.py b/sevenn/train/trainer.py
index 7caf1a0..eb26b60 100644
--- a/sevenn/train/trainer.py
+++ b/sevenn/train/trainer.py
@@ -82,13 +82,15 @@ def from_config(model: torch.nn.Module, config: Dict[str, Any]) -> 'Trainer':
         trainer = Trainer(
             model,
             loss_functions=get_loss_functions_from_config(config),
-            optimizer_cls=optim_dict[config[KEY.OPTIMIZER].lower()],
-            optimizer_args=config[KEY.OPTIM_PARAM],
-            scheduler_cls=scheduler_dict[config[KEY.SCHEDULER].lower()],
-            scheduler_args=config[KEY.SCHEDULER_PARAM],
-            device=config[KEY.DEVICE],
-            distributed=config[KEY.IS_DDP],
-            distributed_backend=config[KEY.DDP_BACKEND]
+            optimizer_cls=optim_dict[config.get(KEY.OPTIMIZER, 'adam').lower()],
+            optimizer_args=config.get(KEY.OPTIM_PARAM, {}),
+            scheduler_cls=scheduler_dict[
+                config.get(KEY.SCHEDULER, 'exponentiallr').lower()
+            ],
+            scheduler_args=config.get(KEY.SCHEDULER_PARAM, {}),
+            device=config.get(KEY.DEVICE, 'auto'),
+            distributed=config.get(KEY.IS_DDP, False),
+            distributed_backend=config.get(KEY.DDP_BACKEND, 'nccl'),
         )
         return trainer