Why does the DateTime.from_naive/2 function tells me the following naive datetime is ambiguous?

Hi all,

I have the following naive datetime: ~N[2020-10-25 02:00:00] and the "Europe/Berlin" timezone. When I want to convert the naive datetime to datetime, I get the following return value from the DateTime.from_naive/2 function:

iex(14)> DateTime.from_naive(~N[2020-10-25 02:00:00], "Europe/Berlin")
{:ambiguous, #DateTime<2020-10-25 02:00:00+02:00 CEST Europe/Berlin>,
 #DateTime<2020-10-25 02:00:00+01:00 CET Europe/Berlin>}

According to the documentation:

When the datetime is ambiguous - for instance during changing from summer to winter time - the two possible valid datetimes are returned. First the one that happens first, then the one that happens after.

As far as I understood it from the Wikipedia’s article about European Summer Time, the change from Summer time to Winter time should happen on the last Sunday of October. In 2020, that would be the 31st of October, not the 25th, so I do not understand what makes this naive datetime ambiguous.

25th October is actually the last Sunday of October 2020. 31st falls on Saturday.



I was confused by my calendar settings where the first day of the week is Sunday instead of Monday …
Thank you for double checking :grinning_face_with_smiling_eyes: