This article explains what versions of Jira can be synchronized with one another using Backbone Issue Sync.
Server ↔ Server
Backbone Issue Sync supports Jira Server versions 7.0 and higher. All supported versions can be synchronized with each other – e.g. you can synchronize a Jira 7.0 instance with a Jira 8.x instance.
We suggest to read the related example use cases, e.g. how to setup a bidirectional synchronization.
If you are using Jira 6.3 or 6.4, we strongly recommend that you upgrade to a current Jira version since Jira 6.3/6.4 have reached their end of life in July 2016/March 2017. If you still want to synchronize with such a Jira, you can install Backbone 3.9.2 on that instance and configure the synchronization in another instance which should be a supported Jira version. Please note that we don't explicitly test this scenario, so future updates may break this compatibility.
Note for the behind the firewall configuration
If you're using the behind the firewall configuration, please make sure that you're using the matching Backbone version for your Jira version. Atlassian's UPM should guide you in choosing the correct version matching your Jira version. Please check the table below for more details on which version to use:
Backbone Version (example with 4.3.3)
|8.4.x and below||4.3.3-pre8.5|
|8.5.0 - 8.5.3, 8.6.0, 8.6.1, 8.7.0, 8.7.1||4.3.3-pre8.5|
|8.5.4, 8.6.2, 8.7.2 (and higher patch version)||4.3.3|
|8.8.0 and higher||4.3.3|