Unable to start embedded Tomcat org.springframework.context.ApplicationContextException

First, you usually can find the root cause on last Caused by statement for debugging.

Therefore, according to the error log you posted, Caused by: org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set should be key!

Although Hibernate is database agnostic, we can specify the current database dialect to let it generate better SQL queries for that database. Therefore, this exception can be solved by simply identifying hibernate.dialect in your properties file as follows:

For application.properties:

spring.jpa.database-platform=org.hibernate.dialect.MySQL5Dialect

For application.yml:

spring:
  jpa:
    database-platform: org.hibernate.dialect.MySQL5Dialect