Fix ConfigurationError deserialization

allennlp/common/checks.py

@@ -5,7 +5,7 @@
 import logging
 import re
 import subprocess
-from typing import List, Union
+from typing import List, Union, Tuple, Any
 
 import torch
 from torch import cuda
@@ -19,6 +19,9 @@ class ConfigurationError(Exception):
     (e.g. missing properties, invalid properties, unknown properties).
     """
 
+    def __reduce__(self) -> Union[str, Tuple[Any, ...]]:
+        return type(self), (self.message,)
+
     def __init__(self, message: str):
         super().__init__()
         self.message = message

tests/training/util_test.py

@@ -191,3 +191,7 @@ def forward(self, **kwargs):
 
         assert metrics["loss"] == float(total_loss / num_batches)
         assert "batch_loss" not in metrics
+
+    def test_exception_serialization(self):
+        e = ConfigurationError('example')
+        assert {'message': 'example'} == vars(pickle.loads(pickle.dumps(e)))