Unable to acquire JDBC Connection

I am using jboss and connection to an RDS instance MariaDB however now getting the below error after around 20 mins of my server being up and running.

"Caused by: javax.persistenceException: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection"

I have restarted MariaDB (Connection max is 150)

Do you have any suggestions on why all of a sudden jboss would start throwing connection errors?