You can upgrade Bugzilla from any version to any later version in one go - there is no need to pass through intermediate versions unless you are changing the method by which you obtain the code along the way.
Upgrading is a one-way process. You cannot "downgrade" an upgraded Bugzilla. If you wish to revert to the old Bugzilla version for any reason, you will have to restore your system from a backup. Those with critical data or large installations may wish to test the upgrade on a development server first, using a copy of the production data and configuration.
Bugzilla uses the Git version control system to store its code. A modern Bugzilla installation consists of a checkout of a stable version of the code from our Git repository. This makes upgrading much easier. If this is already true of your installation, see Upgrading with Git.
Before Git, we used to use Bazaar and, before that, CVS. If your installation of Bugzilla consists of a checkout from one of those two systems, you need to upgrade in three steps:
- Upgrade to the latest point release of your current Bugzilla version.
- Move to Git while staying on exactly the same release.
- Upgrade to the latest Bugzilla using the instructions for Upgrading with Git.
Some Bugzillas were installed simply by downloading a copy of the code as an archive file ("tarball"). However, recent tarballs have included source code management system information, so you may be able to use the Git, Bzr or CVS instructions.
If you aren't sure which of these categories you fall into, to find out which version control system your copy of Bugzilla recognizes, look for the following subdirectories in your root Bugzilla directory:
.git: you installed using Git - follow Upgrading with Git.
.bzr: you installed using Bazaar - follow Migrating from Bazaar.
CVS: you installed using CVS - follow Migrating from CVS.
- None of the above: you installed using an old tarball - follow Migrating from a Tarball.
It is also possible, particularly if your server machine does not have and cannot be configured to have access to the public internet, to upgrade using a tarball. See Upgrading with a Tarball.
Whichever path you use, you may need help with Upgrading a Customized or Extended Bugzilla.
Bugzilla can automatically notify administrators when new releases are available if the upgrade_notification parameter is set. Administrators will see these notifications when they access the Bugzilla home page. Bugzilla will check once per day for new releases. If you are behind a proxy, you may have to set the proxy_url parameter accordingly. If the proxy requires authentication, use the http://user:pass@proxy_url/ syntax.
This documentation undoubtedly has bugs; if you find some, please file them here.