Zootfizzle, one of Blizzard's UI developers, posted a notice this morning to let everyone know of changes made to help minimize unintentional propagation of taint:
With patch 2.3.2 we've made some changes to help minimize unintentional propagation of taint. Since these changes resolved many of the issues presented in this thread's predecessor, we're starting a new one to track issues that have arisen with this patch.
If you get a message that states an "Interface action failed because of an AddOn", it means that an AddOn interfered with the Blizzard UI in some way.
PLEASE CHECK FOR AN UPDATED ADDON, AS YOUR PROBLEM MAY ALREADY BE RESOLVED!
If it still happens, you can diagnose what's going on and let the author know...
To diagnose this, enter the following into chat "/console taintLog 1" and restart the game and try to reproduce it. If you reproduce it, you can quit the game and search through the file Logs\taint.log for the word "blocked". Once you have done this you can turn off logging by entering the following into chat "/console taintLog 0".
Please use this thread to post links to your taint.log file if you get this message.
You'll only get the "blocked" messages in combat, so the easiest way to test this is to go to a low level zone and let a weak creature attack you while you do things involving targeting, group changes, pet changes, etc.
Remember, taint by itself is fine, it only becomes a problem if it results in a "blocked" message.
The previous post can be found here:
On a slightly related note, we've updated the version numbers here on Curse to coincide with the WoW patch today, so you can now flag your AddOn as compatible with 2.3.2.