R.I.P.
Timezone bug in scheduler (Zombie #1)
–
“Came back after daylight saving. Buried again.”
The grave is empty. It rose again.
Death certificate
- Status
- 🪦 Buried
- Cause of death
- TimezoneWorked perfectly, except at midnight UTC, during daylight saving, or for anyone else on Earth.
- Severity
- Critical
- Hours to kill
- 20 hours
- Killed by
- Jashanpreet
- Language
- Python
- Born
- 26 Oct 2025
- Fix merged
- 5 Nov 2025
- Buried
- 14 Nov 2025
- Times resurrected
- 1
- Component
- scheduler
- Symptoms
- After the October clock change, reminders fired an hour late for everyone in Europe.
- The fix
- Recalculated the next run with the user's timezone rules after every clock change.
Timeline
Every life of this bug, oldest first.
Born as “Timezone bug in scheduler”30 Mar 2025
Fix merged9 Apr 2025
Buried18 Apr 2025
Rose again as “Timezone bug in scheduler (Zombie #1)”26 Oct 2025
Fix merged5 Nov 2025
Buried14 Nov 2025
Rose again as “Timezone bug in scheduler (Zombie #2)”29 Mar 2026
Past lives
This bug has died before. Oldest first.
The grave is empty. It rose again.
- this grave
Risen from this grave
It came back.