I’ve run into this error on several new Wordpress upgrades to version 2.5. I originally thought it might be a directory persmissions issue for uploading media or images, but that didn’t fix anything. After a bit of digging around on Google, I uncovered a fix that worked:

Add the following code to the .htaccess file in the /wp-admin/ directory. For me, the .htaccess file did not previously exist, so I just created it with only the following code:


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

Hopefully that helps others having the same problem. If there are other fixes, please feel free to contribute them below.