I never used H2 in the project, but on AWS the logs show a usage of them (after being build with ./gradlew -Dgrails.env=test war). Any Grails 6.0.0 flaw maybe @puneetbehl ? 30-Sep-2023 121114.127 SEVERE [localhost-startStop-1] org.apache.tomcat.jdbc.pool.ConnectionPool.init Unable to create initial connections of pool. org.h2.jdbc.JdbcSQLNonTransientConnectionException: Unsupported connection setting “MVCC” [90113-200] at org.h2.message.DbException.getJdbcSQLException(DbException.java:622) at org.h2.message.DbException.getJdbcSQLException(DbException.java:429) at org.h2.message.DbException.get(DbException.java:205) at org.h2.message.DbException.get(DbException.java:181) at org.h2.engine.ConnectionInfo.readSettingsFromURL(ConnectionInfo.java:269) at org.h2.engine.ConnectionInfo.<init>(ConnectionInfo.java:78) at org.h2.jdbc.JdbcConnection.<init>(JdbcConnection.java:152) at org.h2.Driver.connect(Driver.java:69)

Update: With the hint and help from @Groovy Duke I went over the differences in my build.gradle and gradle.properties with start.grails.org “ideal project configuration” file, and was able to eliminate version hell inconsistencies, and now the project correctly runs in test environment on AWS. I would welcome the link of start.grails.org in the official Grails update documentation, as maybe many developers struggle with #versionhell too. Thanks!