You may likely be hitting bug CSCur95552.
For some reason, Cisco TAC has not documented any work around or fixes at this time.
If running co-resident with CUCM, you need regenerate the IPSec certificate on the node where Prime License Manager is running. Then if this is your CUCM Publisher, restart the DRF Master and DRF Local services. If it's not the Publisher, just restart the DRF Local services.
You should then be able to login.
Regenerate Certificate:
Navigate to Cisco Unified OS Administration | Securtiy | Certificate Management and choose Find.
Scroll down to and choose the ipsec certificate associated with the server where PLM is running co-resident.
Choose Regenerate and wait a few moments until it indicates success.
Restart Services:
Navigate to Cisco Unified Serviceability | Tools | Control Center - Network Services.
Pick the server where PLM is running co-resident and choose Go.
Scroll to and choose Cisco DRF Master, click Restart, and wait until it has been restarted.
Scroll to and choose Cisco DRF Local, click Restart, and wait until it has been restarted.
You should now be able to log into PLM.
Restart Tomcat:
If you experience the same issue, restart Tomcat on the same server and repeat the above steps.
SSH to or open VMware console on server where PLM is co-resident.
Login as the platform administrator.
run "utils service restart Cisco Tomcat"