Upgrading vBulletin 
From time to time it will be necessary to upgrade your vBulletin installation to the latest version, either to gain new features or to fix newly discovered bugs in PHP, MySQL or vBulletin itself.

You can upgrade to the latest version of vBulletin 5 Connect from the following vBulletin versions:The upgrade process differs depending upon the version of vBulletin currently installed on your web server.

When upgrading, the first step is always the same, in that you must log in to the vBulletin Members' Area and download the latest vBulletin package available, as described in the installation instructions.
Warning:
We strongly recommend that you back up your database prior to any upgrade. This will allow you to restore your data should anything happen during the upgrade. The chance of a catastrophic failure is very remote but it can happen.

A document detailing how to back up your database is available in the Technical Documents section of the vBulletin Manual's Appendices, here.
Shane 20th Apr 2005, 10:57am
Be sure to read up on backing up MySQL via telneting into your server. Using phpMyAdmin might cause problems when reloading the database back into sync.

[ Editor: See http://www.vbulletin.com/docs/html/main/maintenance_ssh_backup ]
Brad 20th Apr 2005, 11:03am
If you are in a situation where you can not back-up a large database without error because your host does not support or allow you to use telnet, you can use this php script to back-up safely:

http://www.vbulletin.com/forum/attachment.php?attachmentid=8933

Remember, backing up via the admin cp or phpmyadmin can fail with large databases due to php time outs, this script dose not suffer from such problems.
Andreas 20th Apr 2005, 11:06am
Remember to close down your board prior to upgrading!
Colin 14th Dec 2005, 07:18am
If upgrading from vBulletin 2.x to a 3.x or 3.5.x version, you need to upgrade to *at least* 2.2.9. You can also upgrade to 2.3.5 or whatever is the latest 2.x version though, and continue the upgrade from there.
Mike Pepper 27th May 2007, 09:44am
Re. Using PhpMyAdmin for backup.

There is a very easy way to use PhpMyAdmin for a backup in a situation like this; such as where you want a backup database "image" that you can quickly plug back in if an update were to fail.

For vB updates, do it like this:
1. Shut down your forums.

2. In phpMyAdmin, open the database that you want to copy and click on the "Operations" tab.

3. Find the "Copy Database To:" section and check the (default) options to copy "data and structure" and to "Create database before copying".

4. Give a name for your database that is similar to, but different from your working database, and add put the date in it too. So, for example, if your vB datbase is called "vbdata", you might give the copy the name, "vbd_070526".

5. Click the "Go" button to make the copy. It will take many seconds, or even many, many seconds. (Best to do this in off-traffic hours always.)

6. All done. Your backup database is an exact duplicate of your production database, completely installed and ready to use including all permissions and privileges.

If you ever need to fall back to your backup database all that you have to do is go to the "Operations" tab in phpMyAdmin and rename the database to the name of your production DB. All done!
avalanch 17th May 2010, 04:58am
oh no... god no... do NOT use phpmyadmin for a php backup. The software that me and many many other admins reccomend is mysqldumper, found at mysqldumper.net
Corrie Sloot 28th Oct 2010, 01:26pm
I always preferred using the command-line mysqldump. You would run it with these options: mysqldump --opt -Q -u USERNAME -p DATABASE > DATABASE.TODAYSDATE.sql

Where USERNAME is the database username, DATABASE is the database name and TODAYSDATE is the date, in a format something like 2010-07-20
eva2000 15th Jun 2011, 04:24am
For very large forum upgrades i.e. vB 3.x. to vB 4.x also check out guide written at https://www.vbulletin.com/forum/entry.php/2481-vBulletin-4.x-upgrade-process-for-large-vBulletin-forums-eva2000-s-method
Roberto Muggli 07th Jul 2011, 05:53pm
I would also like to recommend mysqldumper as avalanch did above.

Very simple to use and extremely clear as far as folder permissions and required manual actions are concerned.