WordPress 4-letter comment error

Question

This is one of the weirdest bugs I've seen. I recently uploaded WordPress onto one of my new sites, http://viewmixed.com/, and there is a strange bug when posting four-letter words.

At first I thought you couldn't leave comments at all because I kept trying to leave a comment with the word "test". I then realized that any four letter word seems to break the comments i.e. "four" or "1234", but any other string posts the comment fine.

I have tried deleting all the files/database and then re-installing WP, and that didn't solve anything. I'm on the newest WP version, 3.5.1, and I also tried installing 3.4.2 and 3.1.4, but none fixed the issue...

Anyone have an idea of what could be going on?

EDIT: I forgot to mention that I do have a custom theme right now, but the bug was there before installing the theme, and I also tried changing themes, but the 4-letter bug doesn't go away.

Answer 1

It's not easy to answer this in detail because there are a couple of reasons for getting this error, but as you can see in the title there is an error with 406 Not Acceptable which is probably a MOD_SECURITY problem.

Frist change the permalink settings within WordPress and look if the error still appears.

Second try to deactivate MOD_SECURITY. Therefore you can add a .htaccess file within your wp-admin directory...

<IfModule mod_security.c>
SecFilterScanPOST Off
</IfModule>

...or add a .htaccess file within the root to disable it completely:

<IfModule mod_security.c>
SecFilterEngine Off
</IfModule>

If it still does not work I would suggest to contact your hosting provider to do this for you.

As it is not easy to find the solution for something like this (and for further reading) I suggest reading this blogpost which is on finding the 406 error and this blogpost for another similar solution within WordPress.

Hopefully this might be helpful for you.