In the Jira 7.0 release, we changed the embedded evaluation database from HSQLDB to an H2 database. The H2 database is more stable than HSQLDB, and provides a better first time experience for our customers.

We don't recommend using the embedded  evaluation databases in production, however if you are using a version of Jira prior to 7.0 with the embedded evaluation HSQLDB, and intend to upgrade to a version higher than Jira 7.0, you must first upgrade to a Jira 7.0.x version before upgrading higher. This is because we have specific upgrade tasks we need to run on your data so that you can migrate the data from HSQLDB to the H2 database, and these are only available in the Jira 7.0.x versions.

If you've attempted to upgrade a version of Jira prior to 7.0 to a version higher than 7.0, and you've encountered an error, you have two option for resolution. You can either roll back your upgrade, and upgrade to a Jira 7.0.x version before upgrading higher, or you can roll back and migrate your data to a supported external database, such as PostgreSQL, and then proceed with your upgrade.

Remember, if you're upgrading Jira and plan on jumping several versions, you should always read the release and upgrade notes to help you plan your upgrade. Depending on your configuration, there may be requirements to upgrade to interim versions to ensure your upgrade is as smooth as possible.

• Jira Software release and upgrade notes
• Jira Core release and upgrade notes
• Jira Service Management release and upgrade notes