When testing pandas_udf on group bys, I saw this error with the timestamp column.
File "pandas/_libs/tslib.pyx", line 3593, in pandas._libs.tslib.tz_localize_to_utc
AmbiguousTimeError: Cannot infer dst time from Timestamp('2015-11-01 01:29:30'), try using the 'ambiguous' argument
For details, see Comment box. I'm able to reproduce this on the latest branch-2.3 (last change from Feb 1 UTC)