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Thunderbird Calendar showing incorrect days, shifting events by hours or days.

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Thunderbird 60.9.1 (32-bit) Lightning Calendar is exhibiting huge problems with times and dates. It may or may not be related to the fact that Brazil decided to forego switching to Daylight Saving Time (DST) also called "summer time" in Brazil.

I'm on Windows 10 Professional. My OS is set to Brasilia time. Thunderbird Lightning is set to "America/São Paulo" time.

  • In the Calendar, week 48 for Saturday shows "November 29", but November 29 is a Friday. Similarly Sunday shows "November 30" but Monday shows "December 2".
  • I have an event set to cover December 11 through December 12, as all-day events. They were set in the "America/Los Angeles" time zones. If I edit the event, it only shows December 11 through December 11.
  • It is past midnight in Brazil. If I click on some of these all-day events before midnight, the two-day event would actually show it ending one day before the original event! (As "all-day" events I wouldn't expect the time zone to matter; these should be set to the calendar dates themselves.)

This is just an example of all the day and time shifting going on recently.

Thunderbird 60.9.1 (32-bit) Lightning Calendar is exhibiting huge problems with times and dates. It may or may not be related to the fact that Brazil decided to forego switching to Daylight Saving Time (DST) also called "summer time" in Brazil. I'm on Windows 10 Professional. My OS is set to Brasilia time. Thunderbird Lightning is set to "America/São Paulo" time. * In the Calendar, week 48 for Saturday shows "November 29", but November 29 is a Friday. Similarly Sunday shows "November 30" but Monday shows "December 2". * I have an event set to cover December 11 through December 12, as all-day events. They were set in the "America/Los Angeles" time zones. If I edit the event, it only shows December 11 through December 11. * It is past midnight in Brazil. If I click on some of these all-day events before midnight, the two-day event would actually show it ending one day before the original event! (As "all-day" events I wouldn't expect the time zone to matter; these should be set to the calendar dates themselves.) This is just an example of all the day and time shifting going on recently.

Alle svar (1)

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This does seem to have something to do with Brazilian time. If I set the Thunderbird calendar to "America/São Paulo", here is what it shows for the last week of December of this year, starting on Sunday:

December 29, December 30, December 30, December 31, January 2

Note the duplicate December 30.

If I switch the calendar back to "America/Los Angeles" time, here is what it shows:

December 29, December 30, December 31, January 1, January 2

Thunderbird Calendar is definitely broken dealing with Brazilian time. Please fix this; this is very difficult to use, as days are duplicated, events shift hours and dates, and I have to enter events (even all-day events) on incorrect dates and hope they shift back to the correct dates once they are saved.