Recently I noticed that when creating new WordPress posts I couldn’t use the Flash uploader any more, instead I got a red error simply saying “HTTP Error”. Luckily I have found a fix that works for me courtesy of Kim Woodbridge.

The error seems to revolve around a security issue with mod_security (or at least it did in my instance) and can be easily fixed by adding the following code to your .htaccess file at the root of your WordPress installation:

#BEGIN Image Upload HTTP Error Fix
 <IfModule mod_security.c>
 <Files async-upload.php>
 SecFilterEngine Off
 SecFilterScanPOST Off
 </Files>
 </IfModule>
 #END Image Upload HTTP Error Fix