LUA error without addons

[Incindent-argent-dawn]

47x SharedXML/SharedConstants.lua:42: bad argument #1 to ‘format’ (string expected, got nil)
[string “=[C]”]: in function format' [string "@SharedXML/SharedConstants.lua"]:42: in function GetClassAtlas’
[string “@FrameXML/UnitFrame.lua”]:243: in function UnitFramePortrait_Update' [string "@FrameXML/UnitFrame.lua"]:230: in function <FrameXML/UnitFrame.lua:215> [string "=[C]"]: in function securecall’
[string “@FrameXML/UnitFrame.lua”]:212: in function UnitFrame_SetUnit' [string "@FrameXML/PartyMemberFrame.lua"]:231: in function ToPlayerArt’
[string “@FrameXML/PartyMemberFrame.lua”]:183: in function UpdateArt' [string "@FrameXML/PartyMemberFrame.lua"]:633: in function OnEvent’
[string “@FrameXML/UnitFrame.lua”]:1070: in function <FrameXML/UnitFrame.lua:1068>

Locals:
(*temporary) = “classicon-%s”
(*temporary) = nil
(*temporary) = “string expected, got nil”

[Nariélla-sylvanas]

There may be some vestiges of addons hanging about or leaving their mark. I’d suggest an interface reset. You can see how to do that here:

Resetting the WoW User Interface

[Incindent-argent-dawn]

Cheers.

Figured out that the new Blizzard option to hide class portrait on unitframe was causing the issue.

[Raijin-earthen-ring]

Yep, the new show class icons instead of portrait option is bugged and causes this error. Submit an in game bug if you have the time and inclination.