Fix json normalize 'meta' validation

doc/source/whatsnew/v3.0.0.rst

@@ -1175,6 +1175,7 @@ I/O
 - Fix bug in ``on_bad_lines`` callable when returning too many fields: now emits
   ``ParserWarning`` and truncates extra fields regardless of ``index_col`` (:issue:`61837`)
 - Bug in :func:`pandas.json_normalize` inconsistently handling non-dict items in ``data`` when ``max_level`` was set. The function will now raise a ``TypeError`` if ``data`` is a list containing non-dict items (:issue:`62829`)
+- Bug in :func:`pandas.json_normalize` raising ``TypeError`` when ``meta`` contained a non-string key (e.g., ``int``) and ``record_path`` was specified, which was inconsistent with the behavior when ``record_path`` was ``None`` (:issue:`63019`)
 - Bug in :meth:`.DataFrame.to_json` when ``"index"`` was a value in the :attr:`DataFrame.column` and :attr:`Index.name` was ``None``. Now, this will fail with a ``ValueError`` (:issue:`58925`)
 - Bug in :meth:`.io.common.is_fsspec_url` not recognizing chained fsspec URLs (:issue:`48978`)
 - Bug in :meth:`DataFrame._repr_html_` which ignored the ``"display.float_format"`` option (:issue:`59876`)

pandas/io/json/_normalize.py

@@ -267,6 +267,37 @@ def _simple_json_normalize(
     return normalized_json_object
 
 
+def _validate_meta(meta: str | list[str | list[str]]) -> None:
+    """
+    Validate that meta parameter contains only strings or lists of strings.
+
+    Parameters
+    ----------
+    meta : str or list of str or list of list of str
+        The meta parameter to validate.
+
+    Raises
+    ------
+    TypeError
+        If meta contains elements that are not strings or lists of strings.
+    """
+    if isinstance(meta, str):
+        return
+    for item in meta:
+        if isinstance(item, list):
+            for subitem in item:
+                if not isinstance(subitem, str):
+                    raise TypeError(
+                        "All elements in nested meta paths must be strings. "
+                        f"Found {type(subitem).__name__}: {subitem!r}"
+                    )
+        elif not isinstance(item, str):
+            raise TypeError(
+                "All elements in 'meta' must be strings or lists of strings. "
+                f"Found {type(item).__name__}: {item!r}"
+            )
+
+
 @set_module("pandas")
 def json_normalize(
     data: dict | list[dict] | Series,
@@ -437,6 +468,8 @@ def json_normalize(
 
     Returns normalized data with columns prefixed with the given string.
     """
+    if meta is not None:
+        _validate_meta(meta)
 
     def _pull_field(
         js: dict[str, Any], spec: list | str, extract_record: bool = False

pandas/tests/io/json/test_normalize.py

@@ -927,3 +927,21 @@ def test_series_non_zero_index(self):
             index=[1, 2, 3],
         )
         tm.assert_frame_equal(result, expected)
+
+    def test_json_normalize_meta_string_validation(self):
+        # GH 63019
+        data = [{"a": 1, 12: "meta_value", "nested": [{"b": 2}]}]
+
+        # Test non-string meta raises TypeError consistently
+        with pytest.raises(TypeError, match="must be strings"):
+            json_normalize(data, meta=[12])
+
+        with pytest.raises(TypeError, match="must be strings"):
+            json_normalize(data, record_path=["nested"], meta=[12])
+
+        # Test string meta works correctly
+        result1 = json_normalize(data, meta=["a"])
+        assert "a" in result1.columns
+
+        result2 = json_normalize(data, record_path=["nested"], meta=["a"])
+        assert "a" in result2.columns