Good day, I am having a problem with a migrating data from JIRA 6.4.2 to JIRA 8.1.
We used to have a sub-contractor with a JIRA 6.4.2 site that hosted our JIRA software projects. Now, we purchased our own JIRA software server license and installed the latest version 8 in our environment. We want to import the data form the old 6.4.2 environment into our new environment.
We got the backup of the 6.4.2 data form our contractor.
I followed the steps from the JIRA documentation:
Migrating JIRA applications to another server
https://confluence.atlassian.com/adminjiraserver075/migrating-jira-applications-to-another-server-935390960.html
Everything went well, until I got to step 4.4 ("Import your data").
When I try the import, it gives me the following error: "The xml data you are trying to import is too old to be upgraded by this version of Jira. For more information please see our upgrade documentation: https://confluence.atlassian.com/x/orz9Mw".

Please advise on the best action to take so that we can move our JIRA projects to our new server.