Posted directly from error box, happened after clicking Join Battle on Random Battlegrounds. Issue resolves after reload but comes back sometimes.

Date: 2018-04-14 13:39:27
ID: 1
Error occured in: AddOn: ImprovedBlizzardUI
Count: 1
Message: Error: AddOn ImprovedBlizzardUI attempted to call a forbidden function (JoinBattlefield()) from a tainted execution path.
Debug:
[C]: JoinBattlefield()
Blizzard_PVPUI\Blizzard_PVPUI.lua:611: HonorFrame_Queue()
[string ":OnClick"]:2:
[string ":OnClick"]:1
Locals:
None
AddOns:
Swatter, v7.3.1 (<%codename%>)
AdiBags, vv1.9.8
AdiBagsHearthstones, v7.3-release1
AdiBagsLegionFilters, v1.6.7
ArtifactButton, v5.0
BadBoy, vv7.3.119
BigDebuffs, vv6.4
DBMCore, v7.3.26
DBMDefaultSkin, v
DBMStatusBarTimers, v
Details, v
DetailsDmgRank, v
DetailsDpsTuning, v
DetailsEncounterDetails, v
DetailsRaidCheck, v
DetailsRaidInfoEmeraldNightmare, v
DetailsRaidInfoNighthold, v
DetailsRaidInfoTombOfSargeras, v
DetailsRaidInfoTrialOfValor, v
DetailsStreamer, v
DetailsTimeAttack, v
DetailsTinyThreat, v
DetailsVanguard, v
GatherMate2, v1.41
GladiatorlosSA2, v1.17
Gladius, v5.2.3
ImprovedBlizzardUI, v2.1.0
MasterPlanA, vA
OmniBar, vv8.1
PetBattleTeams, v3.3.9
PetTracker, v7.3.0
PetTrackerBreeds, v7.3.0
PetTrackerConfig, v7.3.0
PetTrackerSwitcher, v7.3.0
PetTrackerUpgrades, v7.3.0
Prat30, vr1082
Prat30Libraries, v
SlideBar, v7.3.1 (<%codename%>)
TidyPlatesThreatPlates, v8.6.5
TradeSkillMaster, ved2ce3c
TradeSkillMasterAppHelper, va8f2b46
WorldQuestTracker, v
XLoot, v7.3-3
XLootFrame, v7.3-3
XLootGroup, v7.3-3
XLootMaster, v7.3-3
XLootMonitor, v7.3-3
ZygorGuidesViewer, v6.1
BlizRuntimeLib_enUS v7.3.5.70300
(ck=4d1)

Been moving into a new place with limited internet. Getting around to this now. Thank you for the report I'll investigate.