What software are you attempting to import from? You can only import a project if it is coming from another instance of JIRA. The following article covers restoring a project from a backup (keep in mind this is only available in JIRA Server):
If you are bringing over data from another company's issue tracker, you will need to import issues into an existing project in JIRA, either via a built in importer or via csv (which depends on the software you are talking about).
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