I have an issue regressing an update from 8.20.1 back to 8.4.2

Question

This is running on a Linux box running Ubuntu 16.04.7 LTS I attempted an upgrade from 8.4.2 to 8.20.1 but, the install required a renewed license which I could not complete so I regressed back to the original version which will not complete it start up sequence. It fails with the following error: 2021-11-11 14:45:56,657 JIRA-Bootstrap ERROR [c.a.jira.upgrade.PluginSystemLauncher] A fatal error occured during initialisation. JIRA has been locked. com.atlassian.jira.InfrastructureException: Error occurred while starting Plugin Manager. null Why is the Plugin Manager set as 'null' ??? When I copied the zip files from the backup it did not retain all the correct ownership mode rules which I had to reinstate even though I used 'unzip -X and I had to remove the plugin directories /plugins/.bundled-plugins /plugins/.osgi-plugins Hope someone can help. Thanks Rick

Nic Brough -Adaptavist- · Accepted Answer

What exactly did you back up and restore when you "regressed"?

Jira doesn't have a downgrade process, you have to roll back to a backup really, if you've not just thrown away all of the upgraded system and gone back to the 8.4 entirely, you may have left 8.20 files all over the place which could easily break when you try to re-run 8.4