Not sure what is going on but I use relatively few addons. And they’re all up to date. I will log in and as soon as I log in I will get an error that an addon has tried to do something forbidden by the UI. If it doesn’t happen as soon as I log in it will happen when I try to do something like check mail or use a hearthstone.
It doesn’t seem to be related to a specific addon. For example: I will log in and TSM will fire the error. So I disable TSM. Then not long after that I log out and in and Wowhead looter will fire the error. So, I disable wowhead looter - then Tom Tom will fire the error. It’s just the weirdest thing. It’s like I can’t use any addons.
Rename your WTF and Cache folders to WTF1 and Cache2. If that doesn’t fix it you can delete the new ones and rename the old ones back to WTF and Cache. If it does fix it you had corrupted files in those folders.
Ask in the tech support forum where they deal with this all the time. Even just reading topics might get you your answer.
It happens to me too, and mostly only in Valdrakken. Is that where you get your action blocked errors too ? I still haven’t found which one is causing this.
And those are taints, so whichever addon that pops up is probably not the culprit, but another sneaky one causing that.