Update: error seems only to happen with my Hunter and Warlock, so chars with pets if that helps sort it out.
On some of my chars (2 out of 13) I get an error when trying to change raid difficulty between normal and heroic:
----------- start error text --------------------
1x …aceBlizzard_UnitPopup/Mainline/UnitPopup.lua:51: bad argument #1 to ‘SetLegacyRaidDifficultyID’ (Usage: SetLegacyRaidDifficultyID(difficultyID [, force]))
[string “=[C]”]: in function SetLegacyRaidDifficultyID' [string "@Blizzard_UnitPopup/Mainline/UnitPopup.lua"]:51: in function SetRaidDifficulties’
[string “@Blizzard_UnitPopupShared/UnitPopupSharedButtonMixins.lua”]:1441: in function <…zard_UnitPopupShared/UnitPopupSharedButtonMixins.lua:1440>
[string “=(tail call)”]: ?
[string “=(tail call)”]: ?
[string “=[C]”]: in function securecallfunction' [string "@Blizzard_Menu/Menu.lua"]:854: in function Pick’
[string “@Blizzard_Menu/MenuTemplates.lua”]:64: in function <Blizzard_Menu/MenuTemplates.lua:58>
Locals:
(*temporary) = nil
(*temporary) = nil
--------------------- end error text ------------------------------------------------