Upgrading an existing Jira instance on Linux is pretty straight forward with the binary installer provided by Atlassian. But do take the time to prepare the upgrade. Preparing the upgrade will be useful during the upgrade.
The installer is probably the easiest way to upgrade Jira but you I do recommend that you check the following as a minimum:
- Check the upgrade path for your Jira instance. Jira admin > Add-ons > Manage apps > JIRA update check. Select the version of Jira you want to upgrade to. Pay attention to the apps that are incompatible.
- Do I have enough disk space for the upgrade? This is VERY important. The upgrade will crash in a bad way if you run out of disk space. Jira will perform backup of the Jira home directory and the old Jira installation directory if you agree to this during the installation. I do recommend you enable the backup. Run the installer in a location where you know there is plenty of space for the installation.