This exception (No managed connections available within configured blocking timeout) occurs mainly due to one of the following reasons:
- The connection pool needs tuning (e.g. max-pool-size and blocking-timeout-millis).
- The application is leaking connections.
- Threads with connections to the database are hanging and holding on to the connections.
What I suggest you is to check first the Example Datasource configurations in the official documentation.
You have to assure that the connections are validated. You can review the Database connection validation in the official documentation.