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BUG: Behavior change in pandas 3.x with <code>Series.resample</code> and <code>closed="right", how="right"</code>

Bug

RegressionFunctionality that used to work in a prior pandas versionFunctionality that used to work in a prior pandas version

Resampleresample methodresample method

Status: Open.

#62200 In pandas-dev/pandas;

· TomAugspurger opened on Aug 26, 2025

· 

3.0

Potential regression induced by "BUG: Use large_string in string array consistently"

Arrowpyarrow functionalitypyarrow functionality

Needs TriageIssue that has not been reviewed by a pandas team memberIssue that has not been reviewed by a pandas team member

RegressionFunctionality that used to work in a prior pandas versionFunctionality that used to work in a prior pandas version

StringsString extension data type and string dataString extension data type and string data

Status: Open.

#58651 In pandas-dev/pandas;

· DeaMariaLeon opened on May 9, 2024

Potential perf regressions introduced by Copy-on-Write

Copy / view semantics

PerformanceMemory or execution speed performanceMemory or execution speed performance

RegressionFunctionality that used to work in a prior pandas versionFunctionality that used to work in a prior pandas version

Status: Open.

#57431 In pandas-dev/pandas;

· rhshadrach opened on Feb 15, 2024

BUG: pandas 2.2.0 <code>DataFrame.groupby</code> regression when group labels of type <code>pd.Timestamp</code>

Bug

IndexRelated to the Index class or subclassesRelated to the Index class or subclasses

RegressionFunctionality that used to work in a prior pandas versionFunctionality that used to work in a prior pandas version

TimezonesTimezone data dtypeTimezone data dtype

Status: Open.

#57192 In pandas-dev/pandas;

· maread99 opened on Feb 1, 2024

BUG: Regression on np.logical_or, it behaves erraticly from 2.0, breaking backwards compatibility

Bug

Compatpandas objects compatability with Numpy or Python functionspandas objects compatability with Numpy or Python functions

RegressionFunctionality that used to work in a prior pandas versionFunctionality that used to work in a prior pandas version

ufuncs__array_ufunc__ and __array_function____array_ufunc__ and __array_function__

Status: Open.

#54416 In pandas-dev/pandas;

· PabloRuizCuevas opened on Aug 4, 2023

BUG: <code>Series.replace</code> converts <code>np.nan</code> into <code>pd.NaT</code> implicitly

Dtype ConversionsUnexpected or buggy dtype conversionsUnexpected or buggy dtype conversions

Missing-datanp.nan, pd.NaT, pd.NA, dropna, isnull, interpolatenp.nan, pd.NaT, pd.NA, dropna, isnull, interpolate

RegressionFunctionality that used to work in a prior pandas versionFunctionality that used to work in a prior pandas version

replacereplace methodreplace method

Status: Open.

#48034 In pandas-dev/pandas;

· ng-henry opened on Aug 11, 2022

BUG: AttributeError: 'bool' object has no attribute 'to_numpy' in "mask_missing" method of core/missing.py

Bug

ConstructorsSeries/DataFrame/Index/pd.array ConstructorsSeries/DataFrame/Index/pd.array Constructors

RegressionFunctionality that used to work in a prior pandas versionFunctionality that used to work in a prior pandas version

replacereplace methodreplace method

SubclassingSubclassing pandas objectsSubclassing pandas objects

Status: Open.

#47101 In pandas-dev/pandas;

· rainnnnny opened on May 24, 2022

BUG: dataframe with datetimeindex as index, when indexing columns interprets some strings as datetimes

Bug

DatetimeDatetime data dtypeDatetime data dtype

IndexingRelated to indexing on series/frames, not to indexes themselvesRelated to indexing on series/frames, not to indexes themselves

RegressionFunctionality that used to work in a prior pandas versionFunctionality that used to work in a prior pandas version

Status: Open.

#47006 In pandas-dev/pandas;

· JamesHowse opened on May 12, 2022

BUG: <code>DataFrame.loc</code> is not consistent with <code>DataFrame.__setitem__</code> when used with 2D numpy array

Bug

IndexingRelated to indexing on series/frames, not to indexes themselvesRelated to indexing on series/frames, not to indexes themselves

RegressionFunctionality that used to work in a prior pandas versionFunctionality that used to work in a prior pandas version

Status: Open.

#46544 In pandas-dev/pandas;

· anmyachev opened on Mar 28, 2022

BUG: Inconsistent assignment of <code>NAT</code> values to datetime columns in <code>MultiIndex</code>

Bug

DatetimeDatetime data dtypeDatetime data dtype

Missing-datanp.nan, pd.NaT, pd.NA, dropna, isnull, interpolatenp.nan, pd.NaT, pd.NA, dropna, isnull, interpolate

MultiIndex

RegressionFunctionality that used to work in a prior pandas versionFunctionality that used to work in a prior pandas version

TimedeltaTimedelta data typeTimedelta data type

Status: Open.

#43351 In pandas-dev/pandas;

· galipremsagar opened on Sep 1, 2021

BUG: behavior change in dataframe.shift(, freq=infer) when upgrading from pandas 1.1.5 to 1.2.x

Bug

FrequencyDateOffsetsDateOffsets

RegressionFunctionality that used to work in a prior pandas versionFunctionality that used to work in a prior pandas version

Status: Open.

#40799 In pandas-dev/pandas;

· laurent-mutricy opened on Apr 6, 2021

BUG: Series.plot.bar() raises TypeError on timedelta dtype

Bug

Missing-datanp.nan, pd.NaT, pd.NA, dropna, isnull, interpolatenp.nan, pd.NaT, pd.NA, dropna, isnull, interpolate

RegressionFunctionality that used to work in a prior pandas versionFunctionality that used to work in a prior pandas version

TimedeltaTimedelta data typeTimedelta data type

Visualizationplottingplotting

Status: Open.

#39320 In pandas-dev/pandas;

· darkdragon-001 opened on Jan 21, 2021