Caused by: oracle.apps.fnd.common.PoolException: Not able to create new database connection: FNDSECURITY_APPL_SERVER_ID

This error is caused when the instance is cloned, wherein the server id might be changed.
Get the new server id by running the query

 select *

from fnd_nodes;

You will find the server_id populated in of the three columns, copy and paste in the respective instance dbc file. Restart the Jdeveloper and the error should be cleared.