@@ -92,12 +92,12 @@ Other enhancements
 - Implemented ``__pandas_priority__`` to allow custom types to take precedence over :class:`DataFrame`, :class:`Series`, :class:`Index`, or :class:`ExtensionArray` for arithmetic operations, :ref:`see the developer guide <extending.pandas_priority>` (:issue:`48347`)
 - Improve error message when having incompatible columns using :meth:`DataFrame.merge` (:issue:`51861`)
 - Improve error message when setting :class:`DataFrame` with wrong number of columns through :meth:`DataFrame.isetitem` (:issue:`51701`)
+- Improved error handling when using :meth:`DataFrame.to_json` with incompatible ``index`` and ``orient`` arguments (:issue:`52143`)
 - Improved error message when creating a DataFrame with empty data (0 rows), no index and an incorrect number of columns. (:issue:`52084`)
 - Let :meth:`DataFrame.to_feather` accept a non-default :class:`Index` and non-string column names (:issue:`51787`)
 - Performance improvement in :func:`read_csv` (:issue:`52632`) with ``engine="c"``
 - Performance improvement in :func:`concat` with homogeneous ``np.float64`` or ``np.float32`` dtypes (:issue:`52685`)
 - Performance improvement in :meth:`DataFrame.filter` when ``items`` is given (:issue:`52941`)
--
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_210.notable_bug_fixes:

@@ -2307,7 +2307,7 @@ def to_json(
 default_handler: Callable[[Any], JSONSerializable] | None = None,
 lines: bool_t = False,
 compression: CompressionOptions = "infer",
-index: bool_t = True,
+index: bool_t | None = None,
 indent: int | None = None,
 storage_options: StorageOptions = None,
 mode: Literal["a", "w"] = "w",
@@ -2376,10 +2376,11 @@ def to_json(
 
 .. versionchanged:: 1.4.0 Zstandard support.
 
-index : bool, default True
-Whether to include the index values in the JSON string. Not
-including the index (``index=False``) is only supported when
-orient is 'split' or 'table'.
+index : bool or None, default None
+The index is only used when 'orient' is 'split', 'index', 'column',
+or 'table'. Of these, 'index' and 'column' do not support
+`index=False`.
+
 indent : int, optional
 Length of whitespace used to indent each record.
 

@@ -100,7 +100,7 @@ def to_json(
 default_handler: Callable[[Any], JSONSerializable] | None = ...,
 lines: bool = ...,
 compression: CompressionOptions = ...,
-index: bool = ...,
+index: bool | None = ...,
 indent: int = ...,
 storage_options: StorageOptions = ...,
 mode: Literal["a", "w"] = ...,
@@ -120,7 +120,7 @@ def to_json(
 default_handler: Callable[[Any], JSONSerializable] | None = ...,
 lines: bool = ...,
 compression: CompressionOptions = ...,
-index: bool = ...,
+index: bool | None = ...,
 indent: int = ...,
 storage_options: StorageOptions = ...,
 mode: Literal["a", "w"] = ...,
@@ -139,15 +139,24 @@ def to_json(
 default_handler: Callable[[Any], JSONSerializable] | None = None,
 lines: bool = False,
 compression: CompressionOptions = "infer",
-index: bool = True,
+index: bool | None = None,
 indent: int = 0,
 storage_options: StorageOptions = None,
 mode: Literal["a", "w"] = "w",
 ) -> str | None:
-if not index and orient not in ["split", "table"]:
+if orient in ["records", "values"] and index is True:
 raise ValueError(
-"'index=False' is only valid when 'orient' is 'split' or 'table'"
+"'index=True' is only valid when 'orient' is 'split', 'table', "
+"'index', or 'columns'."
 )
+elif orient in ["index", "columns"] and index is False:
+raise ValueError(
+"'index=False' is only valid when 'orient' is 'split', 'table', "
+"'records', or 'values'."
+)
+elif index is None:
+# will be ignored for orient='records' and 'values'
+index = True
 
 if lines and orient != "records":
 raise ValueError("'lines' keyword only valid when 'orient' is records")

@@ -1472,17 +1472,34 @@ def test_index_false_to_json_table(self, data):
 
 assert result == expected
 
-@pytest.mark.parametrize("orient", ["records", "index", "columns", "values"])
+@pytest.mark.parametrize("orient", ["index", "columns"])
 def test_index_false_error_to_json(self, orient):
-# GH 17394
+# GH 17394, 25513
 # Testing error message from to_json with index=False
 
 df = DataFrame([[1, 2], [4, 5]], columns=["a", "b"])
 
-msg = "'index=False' is only valid when 'orient' is 'split' or 'table'"
+msg = (
+"'index=False' is only valid when 'orient' is 'split', "
+"'table', 'records', or 'values'"
+)
 with pytest.raises(ValueError, match=msg):
 df.to_json(orient=orient, index=False)
 
+@pytest.mark.parametrize("orient", ["records", "values"])
+def test_index_true_error_to_json(self, orient):
+# GH 25513
+# Testing error message from to_json with index=True
+
+df = DataFrame([[1, 2], [4, 5]], columns=["a", "b"])
+
+msg = (
+"'index=True' is only valid when 'orient' is 'split', "
+"'table', 'index', or 'columns'"
+)
+with pytest.raises(ValueError, match=msg):
+df.to_json(orient=orient, index=True)
+
 @pytest.mark.parametrize("orient", ["split", "table"])
 @pytest.mark.parametrize("index", [True, False])
 def test_index_false_from_json_to_json(self, orient, index):