DatetimeIndex.to_period with freq

[yohplala]

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of pandas (1.0.3).

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Code Sample

# Input date range:
pi5m = pd.date_range(start='2019-12-22 06:40:00+00:00', end='2019-12-22 08:45:00+00:00', freq='5min')

# Converting to PeriodIndex
pi5m.to_period()

  File "/home/p/.local/lib/python3.7/site-packages/pandas/core/arrays/period.py", line 938, in dt64arr_to_periodarr
    freq = Period._maybe_convert_freq(freq)

  File "pandas/_libs/tslibs/period.pyx", line 1580, in pandas._libs.tslibs.period._Period._maybe_convert_freq

AttributeError: 'NoneType' object has no attribute 'n'

# Working
pi5m.to_period('5min')

Problem description

It is specified in documentation that if not provided, freq is inferred.
However, with above-provided input, I get the error message indicated.
Is this a bug?

Thanks for your feedback.
Bests,

[TomAugspurger]

Thanks for the report. Looks like a bug if you're interested in investigating more.

[ShaharNaveh]

take

[yohplala]

Hi, thanks, I am not that at ease with development at the moment.