1x ..._AchievementFilter/Gui/EventReminder/AlertSystem.lua:266: bad argument #1 to '(for generator)' (table expected, got nil)
[string "=[C]"]: in function (for generator)' [string "@Krowi_AchievementFilter/Gui/EventReminder/AlertSystem.lua"]:266: in function ShowUpcomingCalendarEvents'
[string "@Krowi_AchievementFilter/Gui/EventReminder/AlertSystem.lua"]:282: in function `func'
[string "@ElvUI_Libraries/Core/Ace3/AceTimer-3.0-17/AceTimer-3.0.lua"]:57: in function <...UI_Libraries/Core/Ace3/AceTimer-3.0/AceTimer-3.0.lua:50>

Locals:
(*temporary) = nil
(*temporary) = nil
(*temporary) = "table expected, got nil"

I checked and 81.3 was not jet pushed but it is now, please let me know if you still experience the issue.

This one should've been fixed in the latest version 81.3. Is it still happening?

the error was displayed to me yesterday, shortly before I posted it