amazon web services - Spring Boot AWS RDS Proxy Connection issue - Stack Overflow

I am getting below error from spring boot application which is connected to RDS Proxy and RDS Proxy is using Aurora MySQL DB. Any idea how to fix and why we are getting it?

caused by java.sql.SQLTransientConnectionException: HikariPool-1 - Connection is not available, request timed out after 30000ms.
                                                                                                   com.zaxxer.hikari.pool.HikariPool.createTimeoutException(HikariPool.java:696)
                                                                                                            com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:181)