From 7a3b6fe0d04f6fd972e76cc5045cfbb424187854 Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Wed, 15 Jan 2020 03:13:53 -0600
Subject: [PATCH 01/19] GH 30975-Fix for Series.append(DataFrame)

---
 pandas/core/series.py                      | 3 +++
 pandas/tests/series/methods/test_append.py | 9 +++++++++
 2 files changed, 12 insertions(+)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index 33565bbedade6..aa4863586b5b2 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -2538,6 +2538,9 @@ def append(self, to_append, ignore_index=False, verify_integrity=False) -> "Seri
             to_concat = [self]
             to_concat.extend(to_append)
         else:
+            if not isinstance(to_append, type(self)):
+                msg = f"to_append should be a Series or list/tuple of Series, got {type(to_append)}"
+                raise TypeError(msg)
             to_concat = [self, to_append]
         return self._ensure_type(
             concat(
diff --git a/pandas/tests/series/methods/test_append.py b/pandas/tests/series/methods/test_append.py
index dc0fca4bba067..cc50598b4631f 100644
--- a/pandas/tests/series/methods/test_append.py
+++ b/pandas/tests/series/methods/test_append.py
@@ -61,6 +61,15 @@ def test_append_tuples(self):
 
         tm.assert_series_equal(expected, result)
 
+    def test_append_dataframe(self):
+        # GH 30975
+        df = pd.DataFrame({"A": [1, 2], "B": [3, 4]})
+        df2 = pd.DataFrame({"C": [5, 6], "D": [7, 8]})
+
+        expected = pd.Series(pd.concat([df.A, df2.D]))
+        result = df.A.append(df2.D)
+
+        tm.assert_series_equal(expected, result)
 
 class TestSeriesAppendWithDatetimeIndex:
     def test_append(self):

From 8ea217fd6f00bfe8ef72d17001bdd9789ff5b74b Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Wed, 15 Jan 2020 03:44:45 -0600
Subject: [PATCH 02/19] GH 30975-Fix for Series.append(DataFrame)

---
 doc/source/whatsnew/v1.0.0.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v1.0.0.rst b/doc/source/whatsnew/v1.0.0.rst
index c423933d4c438..87c454bc5fceb 100755
--- a/doc/source/whatsnew/v1.0.0.rst
+++ b/doc/source/whatsnew/v1.0.0.rst
@@ -1170,7 +1170,7 @@ Other
 - Bug where :meth:`DataFrame.itertuples` would incorrectly determine whether or not namedtuples could be used for dataframes of 255 columns (:issue:`28282`)
 - Handle nested NumPy ``object`` arrays in :func:`testing.assert_series_equal` for ExtensionArray implementations (:issue:`30841`)
 - Bug in :class:`Index` constructor incorrectly allowing 2-dimensional input arrays (:issue:`13601`, :issue:`27125`)
-
+- :meth:`Series.append` will now raise a ``TypeError`` when passed a DataFrame (:issue:`30975`)
 .. ---------------------------------------------------------------------------
 
 .. _whatsnew_100.contributors:

From d5224386432ddc7cd93ebeebc9b39c252c2e4017 Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Wed, 15 Jan 2020 04:02:40 -0600
Subject: [PATCH 03/19] GH 30975-Fix for Series.append(DataFrame) PEP-8
 compliant

---
 pandas/core/series.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index aa4863586b5b2..faeb6bdbd8fba 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -2539,7 +2539,8 @@ def append(self, to_append, ignore_index=False, verify_integrity=False) -> "Seri
             to_concat.extend(to_append)
         else:
             if not isinstance(to_append, type(self)):
-                msg = f"to_append should be a Series or list/tuple of Series, got {type(to_append)}"
+                msg = f"to_append should be a Series or list/tuple of Series, " \
+                      f"got {type(to_append)}"
                 raise TypeError(msg)
             to_concat = [self, to_append]
         return self._ensure_type(

From b717007ccbde5c0d873843811f22f14a4ae09e14 Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Wed, 15 Jan 2020 04:27:00 -0600
Subject: [PATCH 04/19] GH 30975-Fix for Series.append(DataFrame) Adding
 TypeError Testcase

---
 pandas/tests/series/methods/test_append.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/pandas/tests/series/methods/test_append.py b/pandas/tests/series/methods/test_append.py
index cc50598b4631f..e7dc184406036 100644
--- a/pandas/tests/series/methods/test_append.py
+++ b/pandas/tests/series/methods/test_append.py
@@ -71,6 +71,11 @@ def test_append_dataframe(self):
 
         tm.assert_series_equal(expected, result)
 
+        msg = "to_append should be a Series or list/tuple of Series, got " \
+              "<class 'pandas.core.frame.DataFrame'>"
+        with pytest.raises(TypeError, match=msg):
+            df.A.append(df)
+
 class TestSeriesAppendWithDatetimeIndex:
     def test_append(self):
         rng = date_range("5/8/2012 1:45", periods=10, freq="5T")

From b584b356f1024cef02134662dc3a85a01776e467 Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Wed, 15 Jan 2020 18:40:49 -0600
Subject: [PATCH 05/19] GH 30975-Fix for Series.append(DataFrame) Modified

---
 pandas/core/series.py                      | 14 ++++++++++----
 pandas/tests/series/methods/test_append.py | 19 ++++++++++---------
 2 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index faeb6bdbd8fba..4c7284a23232b 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -2534,15 +2534,21 @@ def append(self, to_append, ignore_index=False, verify_integrity=False) -> "Seri
         """
         from pandas.core.reshape.concat import concat
 
+        is_sequence: bool = False
         if isinstance(to_append, (list, tuple)):
             to_concat = [self]
             to_concat.extend(to_append)
+            is_sequence = True
         else:
-            if not isinstance(to_append, type(self)):
-                msg = f"to_append should be a Series or list/tuple of Series, " \
-                      f"got {type(to_append)}"
-                raise TypeError(msg)
             to_concat = [self, to_append]
+        for x in to_concat[1:]:
+            if isinstance(x, (pd.DataFrame,)):
+                msg = (
+                    f"to_append should be a Series or list/tuple of Series, "
+                    f"got {type(to_append).__name__} "
+                    f'{("of "+type(x).__name__) if is_sequence else ""}'
+                )
+                raise TypeError(msg)
         return self._ensure_type(
             concat(
                 to_concat, ignore_index=ignore_index, verify_integrity=verify_integrity
diff --git a/pandas/tests/series/methods/test_append.py b/pandas/tests/series/methods/test_append.py
index e7dc184406036..1f59471785ec8 100644
--- a/pandas/tests/series/methods/test_append.py
+++ b/pandas/tests/series/methods/test_append.py
@@ -61,20 +61,21 @@ def test_append_tuples(self):
 
         tm.assert_series_equal(expected, result)
 
-    def test_append_dataframe(self):
+    def test_append_dataframe_raises(self):
         # GH 30975
         df = pd.DataFrame({"A": [1, 2], "B": [3, 4]})
-        df2 = pd.DataFrame({"C": [5, 6], "D": [7, 8]})
+        li = [df.B, df]
 
-        expected = pd.Series(pd.concat([df.A, df2.D]))
-        result = df.A.append(df2.D)
-
-        tm.assert_series_equal(expected, result)
-
-        msg = "to_append should be a Series or list/tuple of Series, got " \
-              "<class 'pandas.core.frame.DataFrame'>"
+        msg = "to_append should be a Series or list/tuple of Series, got DataFrame"
         with pytest.raises(TypeError, match=msg):
             df.A.append(df)
+        msg = (
+            "to_append should be a Series or list/tuple of Series,"
+            " got list of DataFrame"
+        )
+        with pytest.raises(TypeError, match=msg):
+            df.A.append(li)
+
 
 class TestSeriesAppendWithDatetimeIndex:
     def test_append(self):

From 1e5e8e7b1e2b16c8f7eeb58e982cc113fcd75923 Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Wed, 15 Jan 2020 19:55:19 -0600
Subject: [PATCH 06/19] GH 30975-Fix for Series.append(DataFrame) Doc Build Fix

---
 doc/source/whatsnew/v1.0.0.rst | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v1.0.0.rst b/doc/source/whatsnew/v1.0.0.rst
index 87c454bc5fceb..67d5d9d8ae166 100755
--- a/doc/source/whatsnew/v1.0.0.rst
+++ b/doc/source/whatsnew/v1.0.0.rst
@@ -1155,6 +1155,7 @@ Other
 - :meth:`DataFrame.to_csv` and :meth:`Series.to_csv` now support dicts as ``compression`` argument with key ``'method'`` being the compression method and others as additional compression options when the compression method is ``'zip'``. (:issue:`26023`)
 - Bug in :meth:`Series.diff` where a boolean series would incorrectly raise a ``TypeError`` (:issue:`17294`)
 - :meth:`Series.append` will no longer raise a ``TypeError`` when passed a tuple of ``Series`` (:issue:`28410`)
+- :meth:`Series.append` will now raise a ``TypeError`` when passed a DataFrame (:issue:`30975`)
 - Fix corrupted error message when calling ``pandas.libs._json.encode()`` on a 0d array (:issue:`18878`)
 - Backtick quoting in :meth:`DataFrame.query` and :meth:`DataFrame.eval` can now also be used to use invalid identifiers like names that start with a digit, are python keywords, or are using single character operators. (:issue:`27017`)
 - Bug in ``pd.core.util.hashing.hash_pandas_object`` where arrays containing tuples were incorrectly treated as non-hashable (:issue:`28969`)
@@ -1170,7 +1171,7 @@ Other
 - Bug where :meth:`DataFrame.itertuples` would incorrectly determine whether or not namedtuples could be used for dataframes of 255 columns (:issue:`28282`)
 - Handle nested NumPy ``object`` arrays in :func:`testing.assert_series_equal` for ExtensionArray implementations (:issue:`30841`)
 - Bug in :class:`Index` constructor incorrectly allowing 2-dimensional input arrays (:issue:`13601`, :issue:`27125`)
-- :meth:`Series.append` will now raise a ``TypeError`` when passed a DataFrame (:issue:`30975`)
+
 .. ---------------------------------------------------------------------------
 
 .. _whatsnew_100.contributors:

From 53f1c112c7c11f043915a2f944f9d115d4c0a1af Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Thu, 16 Jan 2020 20:53:01 -0600
Subject: [PATCH 07/19] GH 31087 Updates ggpy reference to plotnine

---
 doc/source/ecosystem.rst          | 12 ++++++------
 web/pandas/community/ecosystem.md | 11 +++++------
 2 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/doc/source/ecosystem.rst b/doc/source/ecosystem.rst
index 7bd5ba7ecdf0b..5acbd83dc55cf 100644
--- a/doc/source/ecosystem.rst
+++ b/doc/source/ecosystem.rst
@@ -112,16 +112,16 @@ also goes beyond matplotlib and pandas with the option to perform statistical
 estimation while plotting, aggregating across observations and visualizing the
 fit of statistical models to emphasize patterns in a dataset.
 
-`yhat/ggpy <https://github.com/yhat/ggpy>`__
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+`has2k1/plotnine <https://github.com/has2k1/plotnine/>`__
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Hadley Wickham's `ggplot2 <https://ggplot2.tidyverse.org/>`__ is a foundational exploratory visualization package for the R language.
 Based on `"The Grammar of Graphics" <https://www.cs.uic.edu/~wilkinson/TheGrammarOfGraphics/GOG.html>`__ it
 provides a powerful, declarative and extremely general way to generate bespoke plots of any kind of data.
-It's really quite incredible. Various implementations to other languages are available,
-but a faithful implementation for Python users has long been missing. Although still young
-(as of Jan-2014), the `yhat/ggpy <https://github.com/yhat/ggpy>`__ project has been
-progressing quickly in that direction.
+It's really quite incredible. Various implementations to other languages are available.
+A good implementation for Python users is `has2k1/plotnine <https://github.com/has2k1/plotnine/>`__,
+which started as an effort to improve the scaling functionality in
+`yhat/ggpy <https://github.com/yhat/ggpy>`__ formally known as "ggplot for python."
 
 `IPython Vega <https://github.com/vega/ipyvega>`__
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/web/pandas/community/ecosystem.md b/web/pandas/community/ecosystem.md
index af6fd1ac77605..677b329317c8e 100644
--- a/web/pandas/community/ecosystem.md
+++ b/web/pandas/community/ecosystem.md
@@ -84,7 +84,7 @@ pandas with the option to perform statistical estimation while plotting,
 aggregating across observations and visualizing the fit of statistical
 models to emphasize patterns in a dataset.
 
-### [yhat/ggpy](https://github.com/yhat/ggpy)
+### [has2k1/plotnine](https://github.com/has2k1/plotnine/)
 
 Hadley Wickham's [ggplot2](https://ggplot2.tidyverse.org/) is a
 foundational exploratory visualization package for the R language. Based
@@ -92,11 +92,10 @@ on ["The Grammar of
 Graphics"](https://www.cs.uic.edu/~wilkinson/TheGrammarOfGraphics/GOG.html)
 it provides a powerful, declarative and extremely general way to
 generate bespoke plots of any kind of data. It's really quite
-incredible. Various implementations to other languages are available,
-but a faithful implementation for Python users has long been missing.
-Although still young (as of Jan-2014), the
-[yhat/ggpy](https://github.com/yhat/ggpy) project has been progressing
-quickly in that direction.
+incredible. Various implementations to other languages are available.
+A good implementation for Python users is [has2k1/plotnine](https://github.com/has2k1/plotnine/),
+which started as an effort to improve the scaling functionality in
+[yhat/ggpy](https://github.com/yhat/ggpy) formally known as "ggplot for python.".
 
 ### [IPython Vega](https://github.com/vega/ipyvega)
 

From 4e1f6b16d47b59c122b4561a4c92ccfb24d1284e Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Thu, 16 Jan 2020 20:53:01 -0600
Subject: [PATCH 08/19] Revert "GH 31087 Updates ggpy reference to plotnine"

This reverts commit 53f1c112c7c11f043915a2f944f9d115d4c0a1af.
---
 doc/source/ecosystem.rst          | 12 ++++++------
 web/pandas/community/ecosystem.md | 11 ++++++-----
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/doc/source/ecosystem.rst b/doc/source/ecosystem.rst
index 5acbd83dc55cf..7bd5ba7ecdf0b 100644
--- a/doc/source/ecosystem.rst
+++ b/doc/source/ecosystem.rst
@@ -112,16 +112,16 @@ also goes beyond matplotlib and pandas with the option to perform statistical
 estimation while plotting, aggregating across observations and visualizing the
 fit of statistical models to emphasize patterns in a dataset.
 
-`has2k1/plotnine <https://github.com/has2k1/plotnine/>`__
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+`yhat/ggpy <https://github.com/yhat/ggpy>`__
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Hadley Wickham's `ggplot2 <https://ggplot2.tidyverse.org/>`__ is a foundational exploratory visualization package for the R language.
 Based on `"The Grammar of Graphics" <https://www.cs.uic.edu/~wilkinson/TheGrammarOfGraphics/GOG.html>`__ it
 provides a powerful, declarative and extremely general way to generate bespoke plots of any kind of data.
-It's really quite incredible. Various implementations to other languages are available.
-A good implementation for Python users is `has2k1/plotnine <https://github.com/has2k1/plotnine/>`__,
-which started as an effort to improve the scaling functionality in
-`yhat/ggpy <https://github.com/yhat/ggpy>`__ formally known as "ggplot for python."
+It's really quite incredible. Various implementations to other languages are available,
+but a faithful implementation for Python users has long been missing. Although still young
+(as of Jan-2014), the `yhat/ggpy <https://github.com/yhat/ggpy>`__ project has been
+progressing quickly in that direction.
 
 `IPython Vega <https://github.com/vega/ipyvega>`__
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/web/pandas/community/ecosystem.md b/web/pandas/community/ecosystem.md
index 677b329317c8e..af6fd1ac77605 100644
--- a/web/pandas/community/ecosystem.md
+++ b/web/pandas/community/ecosystem.md
@@ -84,7 +84,7 @@ pandas with the option to perform statistical estimation while plotting,
 aggregating across observations and visualizing the fit of statistical
 models to emphasize patterns in a dataset.
 
-### [has2k1/plotnine](https://github.com/has2k1/plotnine/)
+### [yhat/ggpy](https://github.com/yhat/ggpy)
 
 Hadley Wickham's [ggplot2](https://ggplot2.tidyverse.org/) is a
 foundational exploratory visualization package for the R language. Based
@@ -92,10 +92,11 @@ on ["The Grammar of
 Graphics"](https://www.cs.uic.edu/~wilkinson/TheGrammarOfGraphics/GOG.html)
 it provides a powerful, declarative and extremely general way to
 generate bespoke plots of any kind of data. It's really quite
-incredible. Various implementations to other languages are available.
-A good implementation for Python users is [has2k1/plotnine](https://github.com/has2k1/plotnine/),
-which started as an effort to improve the scaling functionality in
-[yhat/ggpy](https://github.com/yhat/ggpy) formally known as "ggplot for python.".
+incredible. Various implementations to other languages are available,
+but a faithful implementation for Python users has long been missing.
+Although still young (as of Jan-2014), the
+[yhat/ggpy](https://github.com/yhat/ggpy) project has been progressing
+quickly in that direction.
 
 ### [IPython Vega](https://github.com/vega/ipyvega)
 

From 041ed129499808bbf694753b352141d06448e6b7 Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Thu, 16 Jan 2020 20:53:01 -0600
Subject: [PATCH 09/19] Revert "GH 31087 Updates ggpy reference to plotnine"

This reverts commit 53f1c112c7c11f043915a2f944f9d115d4c0a1af.

From 721a56074c8e1f7ad78e994b232437f657cff4da Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Fri, 17 Jan 2020 14:04:58 -0600
Subject: [PATCH 10/19] GH 30975-Fix for Series.append(DataFrame) Simple
 message change

---
 pandas/core/series.py | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index 4c7284a23232b..8f0b23b934fe0 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -2534,19 +2534,16 @@ def append(self, to_append, ignore_index=False, verify_integrity=False) -> "Seri
         """
         from pandas.core.reshape.concat import concat
 
-        is_sequence: bool = False
         if isinstance(to_append, (list, tuple)):
             to_concat = [self]
             to_concat.extend(to_append)
-            is_sequence = True
         else:
             to_concat = [self, to_append]
         for x in to_concat[1:]:
             if isinstance(x, (pd.DataFrame,)):
                 msg = (
                     f"to_append should be a Series or list/tuple of Series, "
-                    f"got {type(to_append).__name__} "
-                    f'{("of "+type(x).__name__) if is_sequence else ""}'
+                    f"got {type(to_append).__name__}"
                 )
                 raise TypeError(msg)
         return self._ensure_type(

From f312bae4e6669e29f67e1ac730a4ac0f565abc51 Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Fri, 17 Jan 2020 14:47:42 -0600
Subject: [PATCH 11/19] GH 30975-Fix for Series.append(DataFrame) Simple
 message test change

---
 pandas/tests/series/methods/test_append.py | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/pandas/tests/series/methods/test_append.py b/pandas/tests/series/methods/test_append.py
index 1f59471785ec8..f604d6bd02935 100644
--- a/pandas/tests/series/methods/test_append.py
+++ b/pandas/tests/series/methods/test_append.py
@@ -69,10 +69,7 @@ def test_append_dataframe_raises(self):
         msg = "to_append should be a Series or list/tuple of Series, got DataFrame"
         with pytest.raises(TypeError, match=msg):
             df.A.append(df)
-        msg = (
-            "to_append should be a Series or list/tuple of Series,"
-            " got list of DataFrame"
-        )
+        msg = "to_append should be a Series or list/tuple of Series, got list"
         with pytest.raises(TypeError, match=msg):
             df.A.append(li)
 

From a1ebee2207e11456e14f68db940030969c0749f9 Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Sat, 18 Jan 2020 20:26:56 -0600
Subject: [PATCH 12/19] GH 30975-Fix for Series.append(DataFrame) Removed
 self._ensure_type

---
 pandas/core/series.py                      | 10 ++++------
 pandas/tests/series/methods/test_append.py |  4 +---
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index 8f0b23b934fe0..c4dd23e40a327 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -2540,16 +2540,14 @@ def append(self, to_append, ignore_index=False, verify_integrity=False) -> "Seri
         else:
             to_concat = [self, to_append]
         for x in to_concat[1:]:
-            if isinstance(x, (pd.DataFrame,)):
+            if isinstance(x, ABCDataFrame):
                 msg = (
                     f"to_append should be a Series or list/tuple of Series, "
-                    f"got {type(to_append).__name__}"
+                    f"got {type(x).__name__}"
                 )
                 raise TypeError(msg)
-        return self._ensure_type(
-            concat(
-                to_concat, ignore_index=ignore_index, verify_integrity=verify_integrity
-            )
+        return concat(
+            to_concat, ignore_index=ignore_index, verify_integrity=verify_integrity
         )
 
     def _binop(self, other, func, level=None, fill_value=None):
diff --git a/pandas/tests/series/methods/test_append.py b/pandas/tests/series/methods/test_append.py
index f604d6bd02935..f65072abd9d25 100644
--- a/pandas/tests/series/methods/test_append.py
+++ b/pandas/tests/series/methods/test_append.py
@@ -64,14 +64,12 @@ def test_append_tuples(self):
     def test_append_dataframe_raises(self):
         # GH 30975
         df = pd.DataFrame({"A": [1, 2], "B": [3, 4]})
-        li = [df.B, df]
 
         msg = "to_append should be a Series or list/tuple of Series, got DataFrame"
         with pytest.raises(TypeError, match=msg):
             df.A.append(df)
-        msg = "to_append should be a Series or list/tuple of Series, got list"
         with pytest.raises(TypeError, match=msg):
-            df.A.append(li)
+            df.A.append([df])
 
 
 class TestSeriesAppendWithDatetimeIndex:

From 32d29892ec57234d613770f677f1044c4fb0e910 Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Sat, 18 Jan 2020 21:10:22 -0600
Subject: [PATCH 13/19] GH 30975-Fix for Series.append(DataFrame) Removed
 self._ensure_type return type change

---
 pandas/core/series.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index c4dd23e40a327..862f97dad9b8b 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -2462,7 +2462,7 @@ def searchsorted(self, value, side="left", sorter=None):
     # -------------------------------------------------------------------
     # Combination
 
-    def append(self, to_append, ignore_index=False, verify_integrity=False) -> "Series":
+    def append(self, to_append, ignore_index=False, verify_integrity=False):
         """
         Concatenate two or more Series.
 

From 87ea2aa532efd6cf2ec3c3c5603e957943ef98e8 Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Mon, 20 Jan 2020 04:13:30 -0600
Subject: [PATCH 14/19] GH 30975-Fix for Series.append(DataFrame) 0.25.3
 behaviour

---
 doc/source/whatsnew/v1.0.0.rst             |  1 -
 pandas/core/series.py                      | 13 ++++---------
 pandas/tests/series/methods/test_append.py | 14 +++++++-------
 3 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/doc/source/whatsnew/v1.0.0.rst b/doc/source/whatsnew/v1.0.0.rst
index 67d5d9d8ae166..c423933d4c438 100755
--- a/doc/source/whatsnew/v1.0.0.rst
+++ b/doc/source/whatsnew/v1.0.0.rst
@@ -1155,7 +1155,6 @@ Other
 - :meth:`DataFrame.to_csv` and :meth:`Series.to_csv` now support dicts as ``compression`` argument with key ``'method'`` being the compression method and others as additional compression options when the compression method is ``'zip'``. (:issue:`26023`)
 - Bug in :meth:`Series.diff` where a boolean series would incorrectly raise a ``TypeError`` (:issue:`17294`)
 - :meth:`Series.append` will no longer raise a ``TypeError`` when passed a tuple of ``Series`` (:issue:`28410`)
-- :meth:`Series.append` will now raise a ``TypeError`` when passed a DataFrame (:issue:`30975`)
 - Fix corrupted error message when calling ``pandas.libs._json.encode()`` on a 0d array (:issue:`18878`)
 - Backtick quoting in :meth:`DataFrame.query` and :meth:`DataFrame.eval` can now also be used to use invalid identifiers like names that start with a digit, are python keywords, or are using single character operators. (:issue:`27017`)
 - Bug in ``pd.core.util.hashing.hash_pandas_object`` where arrays containing tuples were incorrectly treated as non-hashable (:issue:`28969`)
diff --git a/pandas/core/series.py b/pandas/core/series.py
index 862f97dad9b8b..177301ba931cc 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -23,7 +23,7 @@
 from pandas._config import get_option
 
 from pandas._libs import index as libindex, lib, reshape, tslibs
-from pandas._typing import Label
+from pandas._typing import Label, FrameOrSeriesUnion
 from pandas.compat.numpy import function as nv
 from pandas.util._decorators import Appender, Substitution
 from pandas.util._validators import validate_bool_kwarg, validate_percentile
@@ -2462,7 +2462,9 @@ def searchsorted(self, value, side="left", sorter=None):
     # -------------------------------------------------------------------
     # Combination
 
-    def append(self, to_append, ignore_index=False, verify_integrity=False):
+    def append(
+        self, to_append, ignore_index=False, verify_integrity=False
+    ) -> FrameOrSeriesUnion:
         """
         Concatenate two or more Series.
 
@@ -2539,13 +2541,6 @@ def append(self, to_append, ignore_index=False, verify_integrity=False):
             to_concat.extend(to_append)
         else:
             to_concat = [self, to_append]
-        for x in to_concat[1:]:
-            if isinstance(x, ABCDataFrame):
-                msg = (
-                    f"to_append should be a Series or list/tuple of Series, "
-                    f"got {type(x).__name__}"
-                )
-                raise TypeError(msg)
         return concat(
             to_concat, ignore_index=ignore_index, verify_integrity=verify_integrity
         )
diff --git a/pandas/tests/series/methods/test_append.py b/pandas/tests/series/methods/test_append.py
index f65072abd9d25..4d64b5b397981 100644
--- a/pandas/tests/series/methods/test_append.py
+++ b/pandas/tests/series/methods/test_append.py
@@ -61,15 +61,15 @@ def test_append_tuples(self):
 
         tm.assert_series_equal(expected, result)
 
-    def test_append_dataframe_raises(self):
+    def test_append_dataframe_regression(self):
         # GH 30975
-        df = pd.DataFrame({"A": [1, 2], "B": [3, 4]})
+        df = pd.DataFrame({"A": [1, 2]})
+        result = df.A.append([df])
+        expected = pd.DataFrame(
+            {0: [1.0, 2.0, None, None], "A": [None, None, 1.0, 2.0]}, index=[0, 1, 0, 1]
+        )
 
-        msg = "to_append should be a Series or list/tuple of Series, got DataFrame"
-        with pytest.raises(TypeError, match=msg):
-            df.A.append(df)
-        with pytest.raises(TypeError, match=msg):
-            df.A.append([df])
+        tm.assert_frame_equal(expected, result)
 
 
 class TestSeriesAppendWithDatetimeIndex:

From 19dcea3e344e5676ff714e68673d1fb0f616b785 Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Mon, 20 Jan 2020 14:23:41 -0600
Subject: [PATCH 15/19] GH 30975-Fix for Series.append(DataFrame) 0.25.3
 behaviour return typing fix

---
 pandas/core/series.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index 177301ba931cc..9521808aeb499 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -23,7 +23,7 @@
 from pandas._config import get_option
 
 from pandas._libs import index as libindex, lib, reshape, tslibs
-from pandas._typing import Label, FrameOrSeriesUnion
+from pandas._typing import FrameOrSeries, Label
 from pandas.compat.numpy import function as nv
 from pandas.util._decorators import Appender, Substitution
 from pandas.util._validators import validate_bool_kwarg, validate_percentile
@@ -2464,7 +2464,7 @@ def searchsorted(self, value, side="left", sorter=None):
 
     def append(
         self, to_append, ignore_index=False, verify_integrity=False
-    ) -> FrameOrSeriesUnion:
+    ) -> FrameOrSeries:
         """
         Concatenate two or more Series.
 

From cdf92ae4cdeb59a1bcff107c2c0a2de343ca2488 Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Mon, 20 Jan 2020 15:16:38 -0600
Subject: [PATCH 16/19] GH 30975-Fix for Series.append(DataFrame) 0.25.3
 behaviour return typing fix

---
 pandas/core/series.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index 9521808aeb499..b415dcc29a952 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -23,7 +23,7 @@
 from pandas._config import get_option
 
 from pandas._libs import index as libindex, lib, reshape, tslibs
-from pandas._typing import FrameOrSeries, Label
+from pandas._typing import FrameOrSeriesUnion, Label
 from pandas.compat.numpy import function as nv
 from pandas.util._decorators import Appender, Substitution
 from pandas.util._validators import validate_bool_kwarg, validate_percentile
@@ -2464,7 +2464,7 @@ def searchsorted(self, value, side="left", sorter=None):
 
     def append(
         self, to_append, ignore_index=False, verify_integrity=False
-    ) -> FrameOrSeries:
+    ) -> FrameOrSeriesUnion:
         """
         Concatenate two or more Series.
 

From a74792146db2c4340ee7ca20b7ee66a71cf614fa Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Mon, 20 Jan 2020 16:14:01 -0600
Subject: [PATCH 17/19] GH 30975-Fix for Series.append(DataFrame) 0.25.3
 behaviour return typing fix

---
 pandas/core/series.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index b415dcc29a952..2076d83248861 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -23,7 +23,7 @@
 from pandas._config import get_option
 
 from pandas._libs import index as libindex, lib, reshape, tslibs
-from pandas._typing import FrameOrSeriesUnion, Label
+from pandas._typing import Label
 from pandas.compat.numpy import function as nv
 from pandas.util._decorators import Appender, Substitution
 from pandas.util._validators import validate_bool_kwarg, validate_percentile
@@ -2462,9 +2462,7 @@ def searchsorted(self, value, side="left", sorter=None):
     # -------------------------------------------------------------------
     # Combination
 
-    def append(
-        self, to_append, ignore_index=False, verify_integrity=False
-    ) -> FrameOrSeriesUnion:
+    def append(self, to_append, ignore_index=False, verify_integrity=False):
         """
         Concatenate two or more Series.
 

From a256fe8573cc16bee1586c558bb0c152eb8728df Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Mon, 20 Jan 2020 23:53:46 -0600
Subject: [PATCH 18/19] GH 30975-Fix for Series.append(DataFrame) 0.25.3
 behaviour return typing fix

---
 pandas/core/series.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index 2076d83248861..b415dcc29a952 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -23,7 +23,7 @@
 from pandas._config import get_option
 
 from pandas._libs import index as libindex, lib, reshape, tslibs
-from pandas._typing import Label
+from pandas._typing import FrameOrSeriesUnion, Label
 from pandas.compat.numpy import function as nv
 from pandas.util._decorators import Appender, Substitution
 from pandas.util._validators import validate_bool_kwarg, validate_percentile
@@ -2462,7 +2462,9 @@ def searchsorted(self, value, side="left", sorter=None):
     # -------------------------------------------------------------------
     # Combination
 
-    def append(self, to_append, ignore_index=False, verify_integrity=False):
+    def append(
+        self, to_append, ignore_index=False, verify_integrity=False
+    ) -> FrameOrSeriesUnion:
         """
         Concatenate two or more Series.
 

From 14e0fb49bee7008ee9c5b98aaadded4bf89daf25 Mon Sep 17 00:00:00 2001
From: Harsha <hvardhan20@gmail.com>
Date: Tue, 21 Jan 2020 00:02:30 -0600
Subject: [PATCH 19/19] GH 30975-Fix for Series.append(DataFrame) 0.25.3
 behaviour return typing fix

---
 pandas/core/series.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/pandas/core/series.py b/pandas/core/series.py
index b415dcc29a952..2076d83248861 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -23,7 +23,7 @@
 from pandas._config import get_option
 
 from pandas._libs import index as libindex, lib, reshape, tslibs
-from pandas._typing import FrameOrSeriesUnion, Label
+from pandas._typing import Label
 from pandas.compat.numpy import function as nv
 from pandas.util._decorators import Appender, Substitution
 from pandas.util._validators import validate_bool_kwarg, validate_percentile
@@ -2462,9 +2462,7 @@ def searchsorted(self, value, side="left", sorter=None):
     # -------------------------------------------------------------------
     # Combination
 
-    def append(
-        self, to_append, ignore_index=False, verify_integrity=False
-    ) -> FrameOrSeriesUnion:
+    def append(self, to_append, ignore_index=False, verify_integrity=False):
         """
         Concatenate two or more Series.