I often have the following errors during the upgrade process:

12x ConvertRatings/ConvertRatings.lua:295: attempt to index a nil value [string "@ConvertRatings/ConvertRatings.lua"]:295: in function <ConvertRatings/ConvertRatings.lua:228> [string "=(tail call)"]: ? [string "=[C]"]: in function securecallfunction'
[string "@SharedXML/Tooltip/TooltipDataHandler.lua"]:60: in function <SharedXML/Tooltip/TooltipDataHandler.lua:55>
[string "@SharedXML/Tooltip/TooltipDataHandler.lua"]:80: in function <SharedXML/Tooltip/TooltipDataHandler.lua:76>
[string "@SharedXML/Tooltip/TooltipDataHandler.lua"]:116: in function <SharedXML/Tooltip/TooltipDataHandler.lua:106>
[string "=[C]"]: in function SetAttribute' [string "@SharedXML/Tooltip/TooltipDataHandler.lua"]:141: in function <SharedXML/Tooltip/TooltipDataHandler.lua:134> [string "@SharedXML/Tooltip/TooltipDataHandler.lua"]:282: in function <SharedXML/Tooltip/TooltipDataHandler.lua:240> [string "=[C]"]: in function securecallfunction'
[string "@SharedXML/Tooltip/TooltipDataHandler.lua"]:237: in function <SharedXML/Tooltip/TooltipDataHandler.lua:236>
[string "=[C]"]: in function ProcessInfo' [string "@SharedXML/Tooltip/TooltipDataHandler.lua"]:449: in function <SharedXML/Tooltip/TooltipDataHandler.lua:444> [string "=[C]"]: in function SetBagItem'
[string "@FrameXML/ContainerFrame.lua"]:1504: in function OnUpdate' [string "@FrameXML/ContainerFrame.lua"]:1471: in function OnEnter'
[string "@Inventorian/Item.lua"]:302: in function <Inventorian/Item.lua:286>

Locals:
self = GameTooltip {
0 =
SetQuestLogRewardSpell = defined @SharedXML/Tooltip/TooltipDataHandler.lua:444
ItemTooltip = Frame {
}
SetHyperlink = defined =[C]:-1
SetAzeriteEssence = defined =[C]:-1
ttBackdropBorderColorApplied = false
SetTraitEntry = defined @SharedXML/Tooltip/TooltipDataHandler.lua:444
ClearBackdrop = defined @SharedXML/Backdrop.lua:282
SetLootCurrency = defined @SharedXML/Tooltip/TooltipDataHandler.lua:444
SetWorldCursor = defined @FrameXML/GameTooltip.lua:952
SetLootItem = defined =[C]:-1
GetSpell = defined @FrameXML/GameTooltip.lua:990
ttGradient = Texture {
}
SetQuestLogSpecialItem = defined @SharedXML/Tooltip/TooltipDataHandler.lua:444
SetRecipeReagentItem = defined =[C]:-1
SetMerchantItem = defined =[C]:-1
TopRightCorner = Texture {
}
ttLastUpdate = 0
SetSocketedRelic = defined @SharedXML/Tooltip/TooltipDataHandler.lua:444
ProcessInfo = defined =[C]:-1
NineSlice = Frame {
}
OnLoad = defined @FrameXML/GameTooltip.lua:927
TopEdge = Texture {
}
SetUnitDebuffByAuraInstanceID = defined =[C]:-1
SetBagItem = defined =[C]:-1
SetBackdropColor = defined @TipTac/ttCore.lua:1771
LeftEdge = Texture {
}
AddLineDataText = defined @SharedXML/Tooltip/TooltipDataHandler.lua:324
SetSpellBookItem = defined =[C]:-1
textLeft1Font = "GameTooltipHeaderText"
SetShapeshift = defined @SharedXML/Tooltip/TooltipDataHandler.lua:444
ttDisplayingUnit = false
SetArtifactPowerByID = defined @SharedXML/Tooltip/TooltipDataHandler.lua:444
textRight2Font = "GameTooltipText"
TopOverlay = Texture {
}
SetSocketedItem = defined @SharedXML/Tooltip/TooltipDataHandler.lua:444
SetUnitDebuff = defined =[C]:-1
SetMountBySpellID = defined @SharedXML/Tooltip/TooltipDataHandler.lua:444
SetBorderBlendMode = defined @SharedXML/Backdrop.lua:266
SetTrainerService = defined @SharedXML/Tooltip/TooltipDataHandler.lua:444
TextLeft1 = GameTooltipTextLeft1 {
}
GetTooltipData = defined @SharedXML/Tooltip/TooltipDataHandler.lua:344
SetLFGDungeonShortageReward = defined =[C]:-1
OnBackdropSizeChanged = defined @SharedXML/Backdrop.lua:182
SetArtifactItem = defined @SharedXML/Tooltip/TooltipDataHandler.lua:444
StatusBar = GameTooltipStatusBar {
}
SetPossession = defined @SharedXML/Tooltip/TooltipDataHandler.lua:444
statusBarPool =

do you have an addon called Inventorian installed? Because it looks like that addon is passing bad info

do you have an addon called Inventorian installed? Because it looks like that addon is passing bad info

Yes, I installed Inventorian. :-P