diff --git a/agora/abc.py b/agora/abc.py
index 2c32876e1af2da3c36207b7fc8177b3d62b7abd7..9c7578092e7ab869e0600ba5bc79abbf3a673f44 100644
--- a/agora/abc.py
+++ b/agora/abc.py
@@ -5,8 +5,8 @@ from copy import copy
 from pathlib import Path, PosixPath
 from typing import Union
 
-from yaml import dump, safe_load
 from flatten_dict import flatten
+from yaml import dump, safe_load
 
 atomic = t.Union[int, float, str, bool]
 
@@ -84,8 +84,9 @@ class ParametersABC(ABC):
         try:
             if Path(source).exists():
                 is_buffer = False
-        except Exception:
-            pass
+        except Exception as _:
+            assert isinstance(source, str), "Invalid source type."
+
         if is_buffer:
             params = safe_load(source)
         else: