Many addons are not updated for the latest patch, so you might find useful this tool (install it as any other addon).

This tool emulates removed/changed functions in Updates 3 to 5, so addons should work with even if they are not updated yet - just enable "Allow out of date addons" option in the addon manager.
However this tool isn't almighty, if some addon uses removed/changed functions before this tool is loaded you will still get an UI error and you will have to wait until that addon is properly updated for the latest patch.

Covered functions:

• Update 3
  • GetBagInfo(bagId)
  • GetItemArmorType(itemLink)
  • GetItemWeaponType(itemLink)
  • GetShortAllianceName(alliance)
• Update 4
  • GetAchievementItemLink(achievementId, rewardIndex, linkStyle)
  • GetAchievementRewardInfo(achievementId, rewardIndex)
  • IsSmithingStyleKnown(styleItemIndex)
  • GetNumLastCraftingResultItems()
• Update 5
  • GetNumHeraldryItems()
  • GetHeraldryItemInfo()
  • BuyHeraldryItem()
  • GetHeraldryItemLink()
  • IsThirdAlchemySlotUnlocked()
  • ZO_OptionsWindow_InitializeControl()
  • IsControlAnOption()
  • ZO_Options_UpdateOption()
  • ZO_Options_SetupSlider()
  • ZO_Options_SetupDropdown()
  • ZO_Options_SetupCheckBox()
  • ZO_Options_OnMouseEnter()
  • ZO_OptionsWindow_LoadDefaults()
  • ZO_OptionsWindow_UpdatePanelOptions()
  • ZO_OptionsWindow_UpdateAllPanelOptions()
  • ZO_OptionsWindow_ChangePanels()
• Update 6
  • GetMaxMountLevel()
  • GetTimeUntilMountCanBeFed()
  • PlayEmote()
  • GetAchievementCategoryInfo()

Update 5 also removes some fonts which were commonly used with LibMediaProvider library. If you are using any addon with this library, you might be interested in my other compatibility addon - LMP Removed Fonts.

Special thanks to merlight for new and corrected code.