diff --git a/oxrlib/loaders.py b/oxrlib/loaders.py
index 95020c97e96216299555d48e08b95868d9f9fe8a..3e4d22b10d7f3b34c24399c30ba86356632d3c23 100644
--- a/oxrlib/loaders.py
+++ b/oxrlib/loaders.py
@@ -1,3 +1,19 @@
+class LoaderError(Exception):
+    pass
+
+
+class LoaderNoDataError(LoaderError):
+    pass
+
+
+class LoaderBadRequestError(LoaderError):
+    pass
+
+
+class LoaderSourceError(LoaderError):
+    pass
+
+
 class FileCache:
     def __init__(self, dir_path, filename_pattern):
         self.dir_path = dir_path
@@ -5,5 +21,7 @@ class FileCache:
 
     def historical(self, date, base):
         path = self.dir_path / self.pattern.format(date=date.isoformat(), base=base)
-        return path.open()
-
+        try:
+            return path.open()
+        except FileNotFoundError as error:
+            raise LoaderNoDataError(path) from error