NullPointerException in Hibernate when connecting to PostgreSQL: sqlExceptionHelper() returns null

Description:
When starting a Spring Boot application with Hibernate and PostgreSQL, I get the following error:

java.lang.NullPointerException: Cannot invoke "org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(java.sql.SQLException, String)"
because the return value of "org.hibernate.resource.transaction.backend.jdbc.internal.JdbcIsolationDelegate.sqlExceptionHelper()" is null

Steps to Reproduce:

Use Spring Boot 3.x with Hibernate 6.x
Configure PostgreSQL as follows:

application.properties:

spring.datasource.url=jdbc:postgresql://localhost:5432/testdb spring.datasource.username=testuser spring.datasource.password=testpass spring.jpa.database-platform=org.hibernate.dialect.PostgreSQLDialect spring.jpa.hibernate.ddl-auto=update

docker-compose.yml:

version: '3.9' services: postgres: image: postgres:16 environment: POSTGRES_USER: testuser POSTGRES_PASSWORD: testpass PGDATA: /data/postgres ports: - "5432:5432"

Start PostgreSQL container and run the Spring Boot app.

Expected Behavior:
Hibernate should connect to PostgreSQL and initialize the schema.

Actual Behavior:
Application fails immediately with a NullPointerException in Hibernate related to sqlExceptionHelper().

Environment:

macOS Ventura
Java 17
Spring Boot 3.3.2
Hibernate 6.x
PostgreSQL 16
Docker 24.x

Notes:

Verified that the database credentials and URL are correct.
Running PostgreSQL locally outside Docker works fine.
Error appears when using Dockerized PostgreSQL with Spring Boot running locally or in another container.

Start by running the configuration in application.properties with the PostgreSQL service from docker-compose.yml, using the stated Spring Boot, Hibernate, and PostgreSQL versions. Compare the Dockerized setup with the locally working PostgreSQL setup and trace the startup failure around sqlExceptionHelper(). Done means the cause is isolated and schema initialization completes without the NullPointerException.