Could not open JPA EntityManager for transaction; nested exception is javax.persistence.PersistenceException

Question

when i run my code, i get this exception:

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully         


        

Answer 1

I was not unable to figure out the exact cause, but I realized that it was because of some thread pools since I was able to connect to the db using the terminal. for checking the connectivity you can use the below command.

psql -h hostname -U username -d database

so restarting the server worked for me.