AllowEncodedSlashes not taking effect?

If you are switching on the AllowEncodedSlashes setting in the apache conf file, and it doesn’t seem to be making any difference, then it may well be because you are using vhosts, and the setting is not automatically propergated through them.

You’ll need to edit the vhost and specify the setting within the config part of the vhost:

<VirtualHost *:80>
    ServerName mytest.local
    DocumentRoot /var/www/site2/
    AllowEncodedSlashes On

Be sure to read all about it, and understand the security risks.