Deploy Heroku

Olá,

Fiz o deploy no Heroku de uma aplicação Spring MVC com Thymeleaf e Spring JPA. Quando é feito o deploy ela funciona sem problemas, mas depois que a máquina faz o stop e o start (estou utilizando os recursos free para testes), não consigo mais acessar, acusando erro do JDBC.

… 111 more
2019-12-04T19:22:46.785525+00:00 app[web.1]: Caused by: java.sql.SQLException: No suitable driver
2019-12-04T19:22:46.785526+00:00 app[web.1]: at java.sql.DriverManager.getDriver(DriverManager.java:315)
2019-12-04T19:22:46.785528+00:00 app[web.1]: at org.apache.commons.dbcp2.BasicDataSource.createConnectionFactory(BasicDataSource.java:2145)
2019-12-04T19:22:46.785529+00:00 app[web.1]: … 116 more
2019-12-04T19:22:46.785530+00:00 app[web.1]:
2019-12-04T19:22:46.785906+00:00 app[web.1]: Dec 04, 2019 7:22:46 PM org.apache.catalina.core.StandardContext startInternal
2019-12-04T19:22:46.785909+00:00 app[web.1]: SEVERE: One or more listeners failed to start. Full details will be found in the appropriate container log file
2019-12-04T19:22:46.792899+00:00 app[web.1]: Dec 04, 2019 7:22:46 PM org.apache.catalina.core.StandardContext startInternal
2019-12-04T19:22:46.792902+00:00 app[web.1]: SEVERE: Context [] startup failed due to previous errors
2019-12-04T19:22:46.796316+00:00 app[web.1]: SEVERE: Context [] failed in [org.apache.catalina.core.StandardContext] lifecycle. Allowing Tomcat to shutdown.
2019-12-04T19:22:46.798452+00:00 app[web.1]: Dec 04, 2019 7:22:46 PM org.apache.catalina.core.ApplicationContext log
2019-12-04T19:22:46.798455+00:00 app[web.1]: INFO: Closing Spring root WebApplicationContext
2019-12-04T19:22:46.805921+00:00 app[web.1]: Dec 04, 2019 7:22:46 PM org.apache.catalina.deploy.NamingResourcesImpl cleanUp
2019-12-04T19:22:46.805926+00:00 app[web.1]: WARNING: Failed to retrieve JNDI naming context for container [StandardEngine[Tomcat].StandardHost[localhost].StandardContext[]] so no cleanup was performed for that container
2019-12-04T19:22:46.805928+00:00 app[web.1]: javax.naming.NamingException: No naming context bound to this class loader

Alguém já passou por isso?