The default logging configuration sets the logging levels so that the log file will provide enough information to monitor the behavior of the runtime and provide clues about what caused a problem. However, the default configuration will not provide enough information to debug most problems. The most useful logger to change when trying to debug an issue with Karaf is the root logger. You will want to set its logging level to DEBUG in the org.ops4j.pax.logging.cfg file.
log4j2.rootLogger.level=DEBUG
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