diff --git a/python/lsst/daf/butler/formatters/file.py b/python/lsst/daf/butler/formatters/file.py
index 8d6eb40ee1..a03fad5820 100644
--- a/python/lsst/daf/butler/formatters/file.py
+++ b/python/lsst/daf/butler/formatters/file.py
@@ -175,10 +175,12 @@ def _coerceBuiltinType(self, inMemoryDataset: Any, writeStorageClass: StorageCla
             and type(inMemoryDataset).__module__ == "builtins"
         ):
             # Try different ways of converting to the required type.
-            if hasattr(writeStorageClass.pytype, "model_validate"):
-                # This is for a Pydantic model.
-                inMemoryDataset = writeStorageClass.pytype.model_validate(inMemoryDataset)
-            elif isinstance(inMemoryDataset, dict):
+            # Pydantic v1 uses parse_obj and some non-pydantic classes
+            # use that convention. Pydantic v2 uses model_validate.
+            for method_name in ("model_validate", "parse_obj"):
+                if method := getattr(writeStorageClass.pytype, method_name, None):
+                    return method(inMemoryDataset)
+            if isinstance(inMemoryDataset, dict):
                 if dataclasses.is_dataclass(writeStorageClass.pytype):
                     # Dataclasses accept key/value parameters.
                     inMemoryDataset = writeStorageClass.pytype(**inMemoryDataset)