Spring boot app fails Method org.postgresql.jdbc4.Jdbc4Connection.createClob() is not yet implemented

The createClob failure may be the likely cause. Similar issue on github https://github.com/pgjdbc/pgjdbc/issues/1102

and solution referenced is

http://vkuzel.blogspot.in/2016/03/spring-boot-jpa-hibernate-atomikos.html

which is to disable usage of JDBC metadata and set the correct dialect.

spring.jpa.properties.hibernate.temp.use_jdbc_metadata_defaults = false
spring.jpa.database-platform=org.hibernate.dialect.PostgreSQL9Dialect

or in YAML:

spring:
  jpa:
    properties:
      hibernate:
        temp:
          use_jdbc_metadata_defaults: false
    database-platform: org.hibernate.dialect.PostgreSQL9Dialect