BUG: `DataFrame.resample()` fails across DST transitions with `NonExistentTimeError` in timezone-aware data

[msobhyy10]

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• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

import pandas as pd

# Example 1

df_1 = pd.DataFrame({
    "timestamp": pd.to_datetime([
        "2024-04-26 01:00:00",  # DST jump in Africa/Cairo
        "2024-04-27 00:00:00",
    ]),
    "value": [1, 2],
})

df_1["timestamp"] = df_1["timestamp"].dt.tz_localize("Africa/Cairo")
df_1 = df_1.set_index("timestamp").resample("D").mean()

# Example 2

df_2 = pd.DataFrame(
    {
        "timestamp": pd.to_datetime([
            "2024-04-24 00:00:00",
            "2024-04-25 00:00:00",
        ]),
        "value": [76.0, 42.0],
    }
)

df_2["timestamp"] = df_2["timestamp"].dt.tz_localize("Africa/Cairo")
df_2 = df_2.set_index("timestamp").resample("D").mean().reset_index()

Issue Description

DataFrame.resample() fails when resampling timezone-aware data that crosses a daylight saving time (DST) boundary.
This happens even when the data itself does not contain the nonexistent local time, because pandas internally generates bin edges that fall into DST gaps.

---

Example 1 — direct DST boundary in data

import pandas as pd

df = pd.DataFrame({
    "timestamp": pd.to_datetime([
        "2024-04-26 01:00:00",  # DST jump in Africa/Cairo
        "2024-04-27 00:00:00",
    ]),
    "value": [1, 2],
})

df = df.tz_localize("Africa/Cairo")
df = df.set_index("timestamp").resample("D").mean()

Error:

NonExistentTimeError: 2024-04-26 00:00:00

---

Example 2 — data before the boundary

df = pd.DataFrame(
    {
        "timestamp": pd.to_datetime([
            "2024-04-24 00:00:00",
            "2024-04-25 00:00:00",
        ]),
        "value": [1, 2],
    }
)

df["timestamp"] = df["timestamp"].dt.tz_localize("Africa/Cairo")
df = df.set_index("timestamp").resample("D").mean().reset_index()

Fails because resample generates a nonexistent edge (2024-04-26 00:00:00).

Expected Behavior

Resampling should produce valid daily bins without raising an error.

Example 1 — direct DST boundary in data

	timestamp	value
0	2024-04-26 01:00:00+03:00	1
1	2024-04-27 00:00:00+03:00	2

---

Example 2 — data before the boundary

	timestamp	value
0	2024-04-24 00:00:00+02:00	1
1	2024-04-25 00:00:00+02:00	2

Installed Versions

INSTALLED VERSIONS

commit : 9c8bc3e
python : 3.11.13
python-bits : 64
OS : Linux
OS-release : 5.15.167.4-microsoft-standard-WSL2
Version : #1 SMP Tue Nov 5 00:21:55 UTC 2024
machine : x86_64
processor :
byteorder : little
LC_ALL : None
LANG : C.UTF-8
LOCALE : en_US.UTF-8

pandas : 2.3.3
numpy : 2.3.3
pytz : 2025.2
dateutil : 2.9.0.post0
pip : 24.0
Cython : None
sphinx : None
IPython : 9.6.0
adbc-driver-postgresql: None
adbc-driver-sqlite : None
bs4 : None
blosc : None
bottleneck : None
dataframe-api-compat : None
fastparquet : None
fsspec : None
html5lib : None
hypothesis : None
gcsfs : None
jinja2 : None
lxml.etree : None
matplotlib : None
numba : None
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
psycopg2 : None
pymysql : None
pyarrow : None
pyreadstat : None
pytest : None
python-calamine : None
pyxlsb : None
s3fs : None
scipy : None
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : None
xlsxwriter : None
zstandard : None
tzdata : 2025.2
qtpy : None
pyqt5 : None