What does it mean when my time-series code (pandas) shows a ValueError for freq T?

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When a time-series code in pandas shows a ValueError for freq T, it means that the given frequency is not valid or cannot be inferred for the datetime index. The “T” frequency refers to minute-level frequency, i.e., the frequency for a time-series data at 1-minute intervals.

This error can occur for several reasons such as an irregular time index or a missing value in the index. To resolve this issue, you can try resampling the data to a regular frequency or checking for missing values in the date-time index.