Reported Issue
The issue is generally reported when trying to open a data source in the Dremio UI and it is logged in the server.log file.
Overview
This article deals with a common error that specifies a different Java Runtime version was used to compile a dependency, rather than the one that's compatible:
The source ["source_name"] is currently unavailable. Metadata is not accessible; please check node health (or external storage) and permissions. Info: [oracle/jdbc/pool/OracleConnectionPoolDataSource has been compiled by a more recent version of the Java Runtime (class file version xx.0), this version of the Java Runtime only recognizes class file versions up to xx.0] Additional actions: [oracle/jdbc/pool/OracleConnectionPoolDataSource has been compiled by a more recent version of the Java Runtime (class file version xx.0), this version of the Java Runtime only recognizes class file versions up to xx.0].
Relevant Versions Tools and Integrations
This article is relevant to all Dremio versions.
Steps to Resolve
1) Please make sure the JAVA version being used is supported in the Dremio release that's in use: https://docs.dremio.com/current/get-started/cluster-deployments/deployment-models/standalone/system-requirements/#java-development-kit
2) If the Dremio code was manually compiled, please check the version being used to do so and make sure it's supported. When compiling the Dremio code, make sure you specify the proper supported version to the compiler if Dremio, as per their specifications.
3) If a specific JAVA version was customized in the dremio-env file, please make sure that's officially supported.
4) Check that the class the error complains about, in this case oracle/jdbc/pool/OracleConnectionPoolDataSource, which may have been pulled into the Gitlab source you're pulling it from, was not built on a different class compatibility specification.
Common Challenges
The main challenge can manifest by a Dremio new install of upgrade running into such errors.