If you just upgraded from version 2.x to 3.0.0 or more, the license needs to be updated.
Check Upgrading to 3.0.0 topic for details.
Follow the Atlassian Marketplace steps
to get or update a valid (or trial) license of the OSLC Connect plugin.
If you just upgraded from version 2.x to 3.0.0 or more, the license needs to be updated.