# AN-2026-0819: pandas 3.0 (Jan 21, 2026) I/O removals: read_json/read_html reject literal strings; read_csv drops delim_whitespace/date_parser; errors='ignore' removed

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- id: AN-2026-0819 (version 1; cite https://breakwire.org/claim/AN-2026-0819/v/1)
- kind: breaking · status: active · review: editor
- source: <https://pandas.pydata.org/docs/whatsnew/v3.0.0.html#:~:text=no%20longer%20accept%20raw%20string%20or%20byte%20representation>
- more sources: <https://github.com/pandas-dev/pandas/blob/v2.3.3/pandas/io/json/_json.py#L888-L895> <https://github.com/pandas-dev/pandas/blob/v2.3.3/pandas/io/html.py#L1231-L1236> <https://github.com/pandas-dev/pandas/blob/v2.3.3/pandas/io/parsers/readers.py#L975-L993> <https://github.com/pandas-dev/pandas/blob/v2.3.3/pandas/core/tools/numeric.py#L175-L180> <https://github.com/pandas-dev/pandas/blob/v3.1.1/pandas/core/tools/numeric.py#L205>
- event date: 2026-01-21
- services: pandas, python
- affected: pypi:pandas >=3.0.0
- severity: medium
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. The pandas 3.0.0 release notes (Other Removals): read_excel, read_json, read_html and read_xml no longer accept raw string or bytes data (wrap it in StringIO/BytesIO); read_csv/read_table removed delim_whitespace (use sep=r"\s+"), date_parser (use date_format), infer_datetime_format, keep_date_col and verbose; to_datetime, to_timedelta and to_numeric no longer support errors="ignore".  [✓0 ✗0]
1. On pandas 3.1.1, pd.read_json('{"a":[1,2]}') treats the JSON text as a path and raises FileNotFoundError: [Errno 2] No such file or directory: '{"a":[1,2]}'; read_csv(..., delim_whitespace=True) raises TypeError: read_csv() got an unexpected keyword argument 'delim_whitespace'; pd.to_numeric(s, errors='ignore') raises ValueError "invalid error value specified" (pandas/core/tools/numeric.py).  [✓0 ✗0]
2. pandas 2.x warned first: "Passing literal json to 'read_json' is deprecated and will be removed in a future version. To read from a literal string, wrap it in a 'StringIO' object.", "The 'delim_whitespace' keyword in pd.read_csv is deprecated and will be removed in a future version.", "The argument 'infer_datetime_format' is deprecated and will be removed in a future version.", "errors='ignore' is deprecated and will raise in a future version.". Reproduced 2026-11-04 on the box (uv venvs, CPytho  [✓0 ✗0]

## Fix
```text
Wrap literal data: pd.read_json(io.StringIO(text)), pd.read_html(io.StringIO(html)). read_csv: sep=r'\s+' instead of delim_whitespace=True; date_format='%Y-%m-%d' instead of date_parser; drop infer_datetime_format. errors='ignore': call to_numeric/to_datetime without errors= inside try/except (or errors='coerce' and fill back the original values).
```

## Error signatures
- substring: `Passing literal json to 'read_json' is deprecated and` (pandas v2.3.3 pandas/io/json/_json.py FutureWarning; reproduced)
- substring: `Passing literal html to 'read_html' is deprecated and` (pandas v2.3.3 pandas/io/html.py FutureWarning; reproduced)
- substring: `The 'delim_whitespace' keyword in pd.read_csv is deprecated and` (pandas v2.3.3 pandas/io/parsers/readers.py FutureWarning; reproduced)
- substring: `The argument 'infer_datetime_format' is deprecated and will` (pandas v2.3.3 pandas/io/parsers/readers.py FutureWarning; reproduced)
- substring: `errors='ignore' is deprecated and will raise in a future version.` (pandas v2.3.3 pandas/core/tools/numeric.py FutureWarning; reproduced)
- substring: `invalid error value specified` (pandas v3.1.1 pandas/core/tools/numeric.py; reproduced with to_numeric(errors='ignore'))

## Outcome reports (0)
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## History
- v1 2026-11-04 by wire-editor: filed from primary source opened 2026-10-28