Addons Break the UI and Lua Errors: Finding the Culprit

Section: Getting started & help 2 min read Vanilla 1.12.1 · x5 Updated 16.09.2026

If the UI went sideways, Lua errors pop up or addon buttons stopped working, a conflict or an outdated addon is to blame. The method is the same: isolate the culprit and update or remove it.

AddonsInterface/AddOns

DebugLua scriptErrors

SearchDisable one by one

Contents

Step 1: enable error reporting
Step 2: disable all addons
Step 3: enable one by one
Step 4: check compatibility
Step 5: clean the settings
Step 6: clear the interface cache
See also

Step 1: enable error reporting

By default Vanilla hides Lua errors. Turn them on to see which addon fails:

/console scriptErrors 1

Relog — now a failure shows a window with the error text and the addon file name.

Step 2: disable all addons

On the character select screen click AddOns and clear all checkboxes. If the UI works fine afterwards, the problem is definitely in the addons.

Step 3: enable one by one

Enable addons in small groups and log in until the error returns. The last one enabled is the culprit. Don't forget to uncheck «Load out of date AddOns» — it lets incompatible modules through.

Step 4: check compatibility

Only 1.12.1 addons work on our server. Signs of a correct addon:

Sign	Meaning
Folder in `Interface/AddOns`	Separate folder with a `.toc` file
`## Interface:` line	Starts with `11200`
Source	Classic 1.12 archives, not retail

Step 5: clean the settings

If an addon broke after an update, delete its old profile in WTF/Account/<login>/SavedVariables (<Addon>.lua files). Settings will rebuild.

Step 6: clear the interface cache

Close the game and delete the Cache and WTF folders (the latter also resets realmlist — set it again). This fixes «stuck» errors after many edits.

FAQ

Why doesn't the addon show up on the character screen?

Usually it is not built for 1.12 or sits in the wrong folder. An addon must extract into Interface/AddOns as its own folder with a .toc file, and its ## Interface line must start with 11200. Retail addons do not work in Vanilla.

How do I enable Lua error display?

Type /console scriptErrors 1 in chat and relog. Now an addon error shows a window with the text and the offending file name, so it is easy to tell which addon to disable or update.

What if an addon broke after an update?

Delete its folder in SavedVariables (WTF/Account/…/SavedVariables) — it stores old settings that may conflict with the new version. The profile will rebuild from scratch.