In most Neo4j server environments, all logs will be found in NEO4J_HOME/logs. However, when Neo4j is running as a service on a Ubuntu (debian) Linux environment, usually installed via apt-get install neo4j or similar, the neo4j.log is not present.

To get the contents of this, since neo4j.log just contains STDOUT content, simply look for the neo4j service log contents using journalctl:

For a complete reference of where logs and other files are located in various environments, please refer to the official documentation:

https://neo4j.com/docs/operations-manual/current/configuration/file-locations/