The errors are displayed in the chat (they are probably displayed there because of the UI). The errors keep going, and I cannot write anything in chat. This also cuts my fps in half (you can see on the right side that I have 100 fps, but it will go as down as 60. I get 150-200 usually).

Did you run /questie clearconfig as advised in the release notes?

Yes, tried that right now. It doesn't fix it.

The error in QuestieNotes is because of the error in QuestieTracker. It's trying to validate against a new config table key ["tracked"]. Open your quest log and make sure everything is "untracked". Then run "/questie clearconfig"... run it a couple of times. Then re-add quests to your tracker.

By the way... when trying to determine an issue this addon is awesome!
http://addons.us.to/addon/improvederrorframe

It will stack all the errors in a neat little box with a stack trace. Usually the very first error is the culprit. It helps in trying to track down an issue. And thanks! Screenshots are awesome too!

That fixed it! Thanks!

I'll add that tip to the post. Thank you for confirming.