What steps will reproduce the problem?

Right click open config.

What version of ThreatClassic2 are you using? (Stating 'latest' is not useful)

ThreatClassic2-v2.34-bcc

Do you have an error log of what happened?

Message: ...c2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:189: attempt to call method 'SetBackdrop' (a nil value)
Time: Wed Jun 2 10:10:09 2021
Count: 3
Stack: ...c2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:189: attempt to call method 'SetBackdrop' (a nil value)
[string "@interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua"]:189: in function ?' [string "@Interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\AceGUI-3.0.lua"]:108: in function <...AddOns\ThreatClassic2\Libs\AceGUI-3.0\AceGUI-3.0.lua:97> [string "@Interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\AceGUI-3.0.lua"]:146: in function Create'
[string "@interface\AddOns\ThreatClassic2\Libs\AceConfig-3.0\AceConfigDialog-3.0\AceConfigDialog-3.0.lua"]:1912: in function Open' [string "@Interface\AddOns\ThreatClassic2\core\core.lua"]:950: in function func'
[string "@interface\FrameXML\UIDropDownMenu.lua"]:960: in function `UIDropDownMenuButton_OnClick'
[string ":OnClick"]:1: in function <[string ":OnClick"]:1>

Locals: frame = {
0 =
}
(*temporary) = nil
(*temporary) = {
0 =
}
(*temporary) =

{
bgFile = "Interface\DialogFrame\UI-DialogBox-Background"
tileSize = 32
edgeFile = "Interface\DialogFrame\UI-DialogBox-Border"
tile = true
edgeSize = 32
insets = {
}
}
(*temporary) = "attempt to call method 'SetBackdrop' (a nil value)"
CreateFrame = defined =[C]:-1
UIParent = UIParent {
0 =
firstTimeLoaded = 1
variablesLoaded = true
}
FrameBackdrop = {
bgFile = "Interface\DialogFrame\UI-DialogBox-Background"
tileSize = 32
edgeFile = "Interface\DialogFrame\UI-DialogBox-Border"
tile = true
edgeSize = 32
insets = {
}
}
Frame_OnShow = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:28
Frame_OnClose = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:32
Frame_OnMouseDown = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:36
Button_OnClick = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:23
PaneBackdrop = {
bgFile = "Interface\ChatFrame\ChatFrameBackground"
tileSize = 16
edgeFile = "Interface\Tooltips\UI-Tooltip-Border"
tile = true
edgeSize = 16
insets = {
}
}
StatusBar_OnEnter = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:71
StatusBar_OnLeave = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:75
Title_OnMouseDown = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:40
MoverSizer_OnMouseUp = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:45
SizerSE_OnMouseDown = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:56
SizerS_OnMouseDown = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:61
SizerE_OnMouseDown = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:66
Type = "Frame"
pairs = defined =[C]:-1
methods = {
OnHeightSet = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:108
OnRelease = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:93
OnWidthSet = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:98
SetStatusText = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:123
OnAcquire = defined @interface\AddOns\ThreatClassic2\Libs\AceGUI-3.0\widgets\AceGUIContainer-Frame.lua:83
Show = defi

Thanks for reporting this. it should be fixed in v2.35.

Note that curseforge has a problem with multi client tocs and might not update unless forced.