Carefully read requirements, they may have changed since you last installed/upgraded your iTop instance :
Why upgrading? What features are brought by new versions:
Before upgrading your iTop instance to a new version, read all migration notes on the upgrade path ! For example if you're upgrading from 2.6.3 to 3.0.0, you must read the following migration notes :
Before upgrading, check all of your installed extensions are compatible with the new version !
List of installed extensions and their version can be found in the “about iTop…” dialog, located in the log-off menu.
Check compatibility by opening each extension documentation.
You should first try the update on a test environment running the same environment (PHP and MySQL version and configuration) and same data !
log/setup-queries-*.sqlfile (this file is generated since 2.5.0) and sometimes they can be executed in advance on a not yet migrated iTop database
If your installed iTop instance is at least in the 2.7.0 version you will be able to use the application upgrader to automate the process ! It is located in the System / Application Upgrade menu.
This is recommended especially for security upgrades, where very few changes are generally made !
The iTop application upgrader will check the system configuration and warn you if the requirements are not met.
If you can't use iTop application updater for any reason (upload size, write permissions, …), use the below manual process.
rm -rf addons datamodels images lib manifest.xml portal application core dictionaries env-test index.php navigator setup webservices approot.inc.php css js pages synchro sources documentation
templates/if present (since 2.7.0)
cp -r ./web/* .
chmod 644 conf/production/config-itop.php