I’m getting an error on some — but not all — pages, a 412 error: “Precondition Failed. The precondition on the request for the URL /wp-comments-post.php evaluated to false.”
If you try to post a comment on the post below, for example, I get the error.
In the support forums, I see something about Bad Behavior, a spam filter, but I use Spam Karma. I deactivated and activated it; no difference.
I also got this error just going from one page in an archive to another.
Any ideas??
: LATER: I just shortened the url and it worked. Have no idea whether that’s the cure. If you get a problem like this on the site, please let me know. thanks.

It is referring to the liberal bias precondition. You apparently tried to post a link that did not meet the liberal bias precondition.
And what about BLACK TIMESDAY?
Cat got your tongue?
412 error refers to the date (4/12/1844) of the treaty to annex the republic of Texas into the United States. It led to many of the current liberal troubles.
Got that error earlier today on the site but it seems to be OK now.
Googled a discussion here that may be helpful.
Jeff, your problem has nothing to do with Bad Behavior, since you aren’t using it. You should contact your hosting provider for further assistance, because this problem is likely to happen again without them making some necessary adjustments.
If it was Bad Behavior, you would know it. The error page is pretty explicit.
IO: Thanks.
Could be it that, indeed, the URL was just too long (it was the entire headline of the post below)?
Length is probably not the issue but the combination of letters might of been. Check with your ISP to make sure that there arent any filters picking up on words. Porn seems to be one of the usual suspects in this case.
There are a few ad hoc fixes for similiar issues below, but I would still defer to your ISP as it seems to be a spam prevention feature gone awry.
http://wordpress.org/support/topic/41629
http://wordpress.org/support/topic/33906
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