pydata · dcherian · May 18, 2023 · Sep 10, 2022 · Sep 10, 2022 · Sep 10, 2022
diff --git a/xarray/core/daskmanager.py b/xarray/core/daskmanager.py
@@ -134,7 +134,7 @@ def map_blocks(
         *args: Any,
         dtype: np.typing.DTypeLike | None = None,
         chunks: tuple[int, ...] | None = None,
-        drop_axis: int | Sequence[int] | None = None,
+        drop_axis: int | Sequence[int] = [],
         new_axis: int | Sequence[int] | None = None,
         **kwargs,
     ):

diff --git a/xarray/core/parallelcompat.py b/xarray/core/parallelcompat.py
@@ -242,7 +242,7 @@ def map_blocks(
         *args: Any,
         dtype: np.typing.DTypeLike | None = None,
         chunks: tuple[int, ...] | None = None,
-        drop_axis: int | Sequence[int] | None = None,
+        drop_axis: int | Sequence[int] = [],
         new_axis: int | Sequence[int] | None = None,
         **kwargs,
     ):