Hi,
You cant upgrade directly from version 2.1 to 3.
You can upgrade the following Prime Infrastructure versions to Prime Infrastructure 3.0:
Cisco Prime Infrastructure 2.2.3
Cisco Prime Infrastructure 2.2.2
Data Center Technology Package 1.0.0 for Cisco Prime Infrastructure 2.2.1
Wireless Technology Package 1.0.0 for Cisco Prime Infrastructure 2.2.1
Cisco Prime Infrastructure 2.2.1
Cisco Prime Infrastructure 2.2
So I would recommend to upgrade first to PI2.2 and then move to 3.0.
Here is the guide:
http://www.cisco.com/c/en/us/td/docs/net_mgmt/prime/infrastructure/3-0/quickstart/guide/cpi_qsg.html#pgfId-116272
Regards
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