http://forum.wampserver.com/read.php?2,149684 

Wampserver is not a basic portable application. Running Wamp64 after copying to a USB U:   requires more modifications. Supposed the original install is J:\wamp64 :

1. Define INSTALL_DIR u:/wamp64 in **u:\wamp64\bin\apache\apache2.4.33\conf\httpd.conf** (only affects internal Wampserver scripts)

1. Replace all j:/wamp64 by u:/wamp64 in files :
   1.** U:\wamp64\bin\apache\apache2.4.33\conf\extra\httpd.vhosts.conf**
   1. All (4) **php.ini** and(8) **phpForApache.ini** files **for all php versions**
   1. All **my.ini** files for all mysql and mariadb versions
   1. in all **wamp64/alias/xxxx.conf** files
   1. in **wampmanager.ini** file

1. Before lauching U:\wamp64\wampmanager.exe "as an administrator" we must delete old services with opening a command windows and type :
    sc delete wampapache64
    sc delete wampmysqld64
    sc delete wampmariadb64

Now we can launch U:\wamp64\wampmanager.exe "as an administrator", the tray icon will be red.
We have to create new services by Left1.Click and
1. Apache 1.> Service 1.> Install service
1. MySQL 1.> Service 1.> Install Service
1. MariaDB 1.> Service 1.> Install Service
1. Start all services

It works, I did it exactly like this, on a U:\wamp64 USB stick after copying my original j:\wamp64 folder.

Important : The USB stick must be NTFS formatted and always take the letter U: at each connection.
