Troubleshooting

A quick reference for enabling verbose Kerberos and Hadoop debug output on the command line, so you can see exactly where authentication is failing.

Enable Kerberos debug logging in a JVM, Spark driver, and Spark executors to troubleshoot SPNEGO and authentication issues. Covers the exact Java system properties, Spark configuration keys, and how to redirect Spark logs to stdout so Kerberos output interleaves with application logs.

A quick guide to diagnosing and resolving the ‘Key has been revoked’ error in the Linux kernel keyring using keyctl commands.

How to set the HDFS Namenode StateChange log level to DEBUG via the web UI or the command line, and when that helps with troubleshooting.

A host health test flags NTP clock drift when the system clock falls out of sync with its NTP servers. This guide walks through diagnosing and resolving common NTP synchronization failures.

A practical cheat sheet of openssl s_client commands for inspecting, verifying, and troubleshooting SSL certificates in production environments.