The recommended method is to upgrade on two phase actually, first to 4.4 (or 4.3.x-4.4.x) then to 5.1. This is to ensure that the major migration process done in one upgrade phase so that the troubleshooting process will be easier if something happen.
For your information, JIRA 4.3.x-4.4.x is where the user migration occurred, then you could go straight to 5.x. However as describe earlier, it is recommended to upgrade to 4.4.x.
Before performing any upgrade on production please test the upgrade on a test instance.
My recommendation would be 4.2 -> 4.4 -> 5.2
For more detailed information on the upgrading process, you can refer to this documentation : https://confluence.atlassian.com/display/JIRA/Upgrading+JIRA
if you plant to migrate JIRA to another server on the process of upgrading, you can refer to this documentation as well:
Please do take not that If you are migrating your JIRA, you might want to take note that your JIRA attachment files are not in your database, or in any XML backups, rather you would have to transfer the file from your old JIRA Home to your new JIRA Home.
Badges are a great way to show off community activity, whether you’re a newbie or a Champion.Learn more
Hi Atlassian Community! My name is Shana, and I’m on the Jira Software team. One of the many reasons this Community exists is to connect you to others on similar product journeys or with comparabl...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs