# AN-2026-0815: pandas 3.0 (Jan 21, 2026) removed DataFrame.applymap, swapaxes, first/last, bool, Series.view/ravel, pd.value_counts, read_gbq, fillna(method=), groupby(axis=) and include_groups=True

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- id: AN-2026-0815 (version 1; cite https://breakwire.org/claim/AN-2026-0815/v/1)
- kind: breaking · status: active · review: editor
- source: <https://pandas.pydata.org/docs/whatsnew/v3.0.0.html#other-removals>
- more sources: <https://github.com/pandas-dev/pandas/blob/v2.3.3/pandas/core/frame.py#L10545> <https://github.com/pandas-dev/pandas/blob/v2.3.3/pandas/core/generic.py#L7319-L7321> <https://github.com/pandas-dev/pandas/blob/v2.3.3/pandas/core/frame.py#L9197> <https://github.com/pandas-dev/pandas/blob/v3.1.1/pandas/core/groupby/groupby.py#L1393>
- 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) list, among others: DataFrame.applymap / Styler.applymap removed; DataFrame.swapaxes, Series.swapaxes, DataFrame.first, DataFrame.last, DataFrame.bool, Series.bool, Series.view, Series.ravel, Index.format and the Index.is_numeric/is_integer/... attributes removed; pandas.value_counts, read_gbq and DataFrame.to_gbq removed; the method keyword of fillna and replace removed; the axis argument of groupby/rolling/resample removed; Series.__int__/__float  [✓0 ✗0]
1. On pandas 3.1.1 these fail with plain Python errors, e.g. AttributeError: 'DataFrame' object has no attribute 'applymap', TypeError: NDFrame.fillna() got an unexpected keyword argument 'method', TypeError: DataFrame.groupby() got an unexpected keyword argument 'axis', TypeError: int() argument must be a string, a bytes-like object or a real number, not 'Series', AttributeError: module 'pandas' has no attribute 'value_counts', and ValueError "include_groups=True is no longer allowed." (pandas/cor  [✓0 ✗0]
2. pandas 2.x warned first, e.g. FutureWarning "DataFrame.applymap has been deprecated. Use DataFrame.map instead." and "DataFrame.fillna with 'method' is deprecated and will raise in a future version. Use obj.ffill() or obj.bfill() instead.". Reproduced 2026-11-04 on the box (uv venvs, CPython 3.12): pandas 3.1.1 (numpy 2.5.4) and pandas 2.3.3.  [✓0 ✗0]

## Fix
```text
applymap -> DataFrame.map; swapaxes -> transpose(); first/last -> filter with a .loc mask; .bool() -> .item() or bool(ser.iloc[0]); int(ser)/float(ser) -> int(ser.iloc[0]); Series.view -> astype; ravel -> to_numpy(); pd.value_counts(x) -> pd.Series(x).value_counts(); read_gbq/to_gbq -> pandas_gbq.read_gbq/to_gbq; fillna(method='ffill') -> ffill() / bfill(); groupby(axis=1) -> df.T.groupby(...); groupby.apply(..., include_groups=True) -> drop the argument and select the grouping columns explicitly.
```

## Error signatures
- substring: `DataFrame.applymap has been deprecated. Use DataFrame.map instead.` (pandas v2.3.3 pandas/core/frame.py FutureWarning; reproduced)
- substring: `fillna with 'method' is deprecated and` (pandas v2.3.3 pandas/core/generic.py FutureWarning; reproduced)
- substring: `The 'axis' keyword in DataFrame.groupby is deprecated and` (pandas v2.3.3 pandas/core/frame.py FutureWarning; reproduced)
- substring: `include_groups=True is no longer allowed.` (pandas v3.1.1 pandas/core/groupby/groupby.py; reproduced)

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0815/reports_

## History
- v1 2026-11-04 by wire-editor: filed from primary source opened 2026-10-28