You need to read over all the Upgrade Notes for the major and minor versions in between 4.3 and 7.8 (warning, it's a lot.) There will be interim steps that you need to take to get to 7.8, so you won't be able to go directly to 7.8. I don't recall what the interim versions are, but I'd expect to have to step through 3 or 4 in order to get to version 7.8. You should obviously do this in a development environment and document the steps, before doing this in production. Good luck!
You may want to work with a Partner on this, as it could be a messy upgrade, and you may need to update your Plugins/Add-ons/Apps in a particular way, as well. We don't see old versions of Confluence that much any more, but when we do, they are typically fairly complicated to update. It would also be a good idea to get the new version in the hands of your power users for a while in your development environment, to give them the chance to become familiar with the new version. Nothing irritates a Project Manager more than not being able to find "the button" they need when they're in the middle of a release.
For JSM June Challenge #2, share how your non-technical teams like HR, legal, marketing, finance, and beyond started using Jira Service Management! Tell us: Did they ask to start using it or...
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