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 6.3 and higher. All supported versions can be synchronized with each other – e.g. you can synchronize a Jira 6.3 instance with a Jira 7.x instance.
We suggest to read the related example use cases, e.g. how to setup a bidirectional synchronization.
Server ↔ Cloud or Cloud ↔ Server
All supported versions of Jira Server can be synchronized with Jira Cloud and vice versa. In this case, a synchronization needs to be configured on the Jira Server side. Please read this Example Use Case article which explains the initial setup steps and best practices. However, please note that distributed configurations are not supported.
Cloud ↔ Cloud
Also Jira Cloud instances can be synchronized with each other. This is documented in the cloud section of our documentation.