New game, new client, hundreds of addons updated in a hurry: errors are part of launch month. Handled well, they are a minor annoyance. Handled badly, a popup interrupts you mid-pull and nobody ever fixes the cause.

Collect errors quietly

Install BugGrabber and BugSack. BugGrabber catches errors as they happen and stops the default popup; BugSack gives you a minimap icon and a window to read them later. Turn off the game's own "Display Lua errors" option so you only use one.

Find the culprit

The first line of an error usually names a file path such as Interface/AddOns/SomeAddon/Core.lua:123. The folder after AddOns is your suspect. If the path points to a library folder (Libs, Ace3, LibStub), the addon that bundles it is still the one to look at.

When the path isn't clear:

  1. Disable half your addons, /reload, repeat what caused the error.
  2. If it's gone, the culprit is in the half you disabled. If not, it's in the other half.
  3. Keep halving. Even with fifty addons, it takes six or seven rounds.

Report it usefully

Authors get many reports that say "it's broken". The ones that get fixed include:

  • the addon's version number (from its folder or the AddOns list);
  • that you're on WoW Forever, not retail or Classic, and which preset;
  • the full first error from BugSack, copied as text;
  • what you were doing when it happened;
  • whether it still happens with only that addon enabled.

Post it where the author asks for reports (usually the issues page on GitHub or the comments on CurseForge). Then add a short note to our forum's Compatibility board so other players know, and we'll update the addon's status.