From a438f02fd7e20ab1b268b096536170852bbcec62 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Wed, 25 Jan 2023 14:05:34 -0800
Subject: [PATCH 1/2] BUG: df_empty.convert_dtypes() with pyarrow backend

---
 pandas/core/arrays/arrow/array.py                | 16 +++++++++-------
 .../tests/frame/methods/test_convert_dtypes.py   |  7 +++++++
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/pandas/core/arrays/arrow/array.py b/pandas/core/arrays/arrow/array.py
index 0e70b3795bc85..57759af23ddd5 100644
--- a/pandas/core/arrays/arrow/array.py
+++ b/pandas/core/arrays/arrow/array.py
@@ -137,15 +137,17 @@ def to_pyarrow_type(
     Convert dtype to a pyarrow type instance.
     """
     if isinstance(dtype, ArrowDtype):
-        pa_dtype = dtype.pyarrow_dtype
+        return dtype.pyarrow_dtype
     elif isinstance(dtype, pa.DataType):
-        pa_dtype = dtype
+        return dtype
     elif dtype:
-        # Accepts python types too
-        pa_dtype = pa.from_numpy_dtype(dtype)
-    else:
-        pa_dtype = None
-    return pa_dtype
+        try:
+            # Accepts python types too
+            # Doesn't handle all numpy types
+            return pa.from_numpy_dtype(dtype)
+        except pa.ArrowNotImplementedError:
+            pass
+    return None
 
 
 class ArrowExtensionArray(OpsMixin, ExtensionArray):
diff --git a/pandas/tests/frame/methods/test_convert_dtypes.py b/pandas/tests/frame/methods/test_convert_dtypes.py
index aaccaff0c0c42..cac10c4cbfa68 100644
--- a/pandas/tests/frame/methods/test_convert_dtypes.py
+++ b/pandas/tests/frame/methods/test_convert_dtypes.py
@@ -120,3 +120,10 @@ def test_pyarrow_dtype_backend_from_pandas_nullable(self):
             }
         )
         tm.assert_frame_equal(result, expected)
+
+    def test_pyarrow_dtype_empty_object(self):
+        # GH 50970
+        expected = pd.DataFrame(columns=[0])
+        with pd.option_context("mode.dtype_backend", "pyarrow"):
+            result = expected.convert_dtypes()
+        tm.assert_frame_equal(result, expected)

From bb68f3d3a5c9ca823f2a913c582985bcd6533e37 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Wed, 25 Jan 2023 14:53:51 -0800
Subject: [PATCH 2/2] importorskip

---
 pandas/tests/frame/methods/test_convert_dtypes.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pandas/tests/frame/methods/test_convert_dtypes.py b/pandas/tests/frame/methods/test_convert_dtypes.py
index cac10c4cbfa68..919d25f5ba993 100644
--- a/pandas/tests/frame/methods/test_convert_dtypes.py
+++ b/pandas/tests/frame/methods/test_convert_dtypes.py
@@ -123,6 +123,7 @@ def test_pyarrow_dtype_backend_from_pandas_nullable(self):
 
     def test_pyarrow_dtype_empty_object(self):
         # GH 50970
+        pytest.importorskip("pyarrow")
         expected = pd.DataFrame(columns=[0])
         with pd.option_context("mode.dtype_backend", "pyarrow"):
             result = expected.convert_dtypes()