Moving Servers 
There are two major parts to successfully move your vBulletin forums from one server to another. These are:

1. The vBulletin files, including all the vB files currently on your server as well as any attachments, avatars and profile pics (if you store these in the file system instead of the database) along with any custom images.

2. The vBulletin database which contains the actual data itself, including the user info, posts, threads, forums, setting, styles, languages, etc.

This guide will help you move your vBulletin forum from one server to another. Please note that while you can move the files themselves with FTP, moving the database generally requires Telnet or SSH access to both servers. (Other methods are available but are less reliable.)

If you only have this access on one of the servers, you may need to ask your host to assist you with the steps you cannot perform.
Warning:
Specific cookie domains (Cookie Domain) and cookie paths (Path to Save Cookies) may cause problems if you are moving servers and changing the URL to your forums.

If you are unsure whether your cookie settings will cause problems after the move, we recommend resetting your cookie path to / and removing any cookie domain value before the move. An incorrectly set cookie domain or path will likely prevent you from accessing your control panel.
Dan G. Lunde 04th May 2008, 11:29pm
"Specific cookie domains (Cookie Domain) and cookie paths (Path to Save Cookies) may cause problems if you are moving servers and changing the URL to your forums.

If you are unsure whether your cookie settings will cause problems after the move, we recommend resetting your cookie path to / and removing any cookie domain value before the move. An incorrectly set cookie domain or path will likely prevent you from accessing your control panel."

I copied my production system to my localhost for testing purposes, and now I have this exact problem. The cookie domain is still .domain.com when it should be blank or localhost. But, where do I set this? A link on this page would be of great help!

It is *not* listed in my default config.php, I only have cookie prefix which is still set to vb as per default. I have deleted all cookies, ran tools.php to reset cookie domain and path, but still tools.php lists the cookie domain to be .domain.com. I have also tried manually deleting sessions from the database.
Evans Craig 04th Apr 2010, 03:24pm
Did you ever find the answer to this cookie path issue?
I am getting the same issue of no ctl panel??
Hellen Lowers 14th Apr 2016, 03:17am
Was there ever a response to this? I am trying to fix this same issue as well and haven't been able to find anything on vbulletin forums that designates which actual file has the cookies listed in it to manually change.
Trevor Hannant 14th Apr 2016, 03:19am
As per the warning text:

"If you are unsure whether your cookie settings will cause problems after the move, we recommend resetting your cookie path to / and removing any cookie domain value before the move. An incorrectly set cookie domain or path will likely prevent you from accessing your control panel."

Essentially:

- close your site via AdminCP
- make the changes in AdminCP and save
- backup the database
- reset the cookie values on live site
- re-open site via AdminCP

You then have a 'clean' database backed up in terms of the cookie values.