ErrorMonster is a small addon to block a few standard action errors from printing. Please note that it does not block the "Error Speech" that comes with them - you have to disable that in Sound Options.

It was originally based on RogueSpam, but has since evolved drastically lately after people asked me to add some stuff to it.

Not only does it come with a significant set of default filters, you can of course add and remove filters at will. Filtering does not necessarily mean that the errors are eaten; they can also be redirected to a sink, such as ChatFrame1-7, BigWigs, SCT ( Message), MSBT or Blizzards own FCT, of course, since I implemented sinks, I had to implement general error throttling as well.

You can tell it to also aggro on system and information messages, like quest updates ("1/5 wild boars slain!"), and flush those out the sink as well. And it features a berserk option that will unconditionally flush anything down the sink.