Hi @Daryl Harrison,
According to the Multi-Project Management for JIRA plugin page, its latest vversion is compatible with JIRA Server 5.0 to 6.4.6. It's not clear which JIRA version you're running.
Also according to the plugin page, this is how you should install it:
If this answer was helpful, please allow me to ask you to mark my answer as accepted in order to have it in the top of the thread, also helping other customers.
Thanks in advance!
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