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https://issues.apache.org/jira/browse/CAMEL-25876?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Claus Ibsen resolved CAMEL-25876.
---------------------------------
Resolution: Fixed
> camel-main - log why Camel Main failed to start, once, instead of only the
> JVM printing it on stderr
> ----------------------------------------------------------------------------------------------------
>
> Key: CAMEL-25876
> URL: https://issues.apache.org/jira/browse/CAMEL-25876
> Project: Camel
> Issue Type: Improvement
> Components: camel-main
> Reporter: Claus Ibsen
> Assignee: Claus Ibsen
> Priority: Minor
> Fix For: 4.24.0
>
>
> A Camel Main application that fails to start does not log why.
> {{MainSupport.run()}} passes a failure to start to the caller on purpose ("if
> we have an issue starting then propagate the exception to caller"), and only
> logs failures that happen while running. The main class of an application
> ({{main.run(args)}} in the main class of camel export, the archetypes and
> most applications) does not catch it, so the exception leaves {{main()}} and
> only the JVM prints it, on stderr:
> {noformat}
> 2026-10-20 09:55:49.909 INFO 16017 --- [main]
> he.camel.cli.connector.LocalCliConnector : Camel CLI connector enabled
> Exception in thread "main" java.lang.reflect.InvocationTargetException
> at
> org.springframework.boot.loader.launch.Launcher.launch(Launcher.java:106)
> ...
> Caused by: org.apache.camel.FailedToCreateRouteException: Failed to create
> route: boom ...
> {noformat}
> (the launcher of the fat jar calls main by reflection, hence the
> InvocationTargetException). So the log file of the application ends before
> the failure. That matters in production, where an application often logs to a
> file, and for camel run --runtime=main, whose log is kept as the previous run
> (CAMEL-25832): camel log --previous and the AI tools of the camel-jbang-mcp
> server have no reason to show.
> KameletMain, which camel run uses by default, already logs it ({{doFail}}:
> "Error starting Camel"). Spring Boot logs "Application run failed" and
> Quarkus "Failed to start application", each once.
> Proposal:
> * {{MainSupport.logStartupFailure(e)}} logs "Error starting Camel: ..." with
> the stack trace. {{Main}} (and so the fat-jar {{Main}} of camel export) and
> {{KameletMain}} call it from {{doFail}}. It is not in the base class, as
> Camel Quarkus extends {{MainCommandLineSupport}} and logs the failure itself.
> * As Spring Boot does, the JVM then does not print the same failure a second
> time when it leaves main: the thread that started Camel gets an uncaught
> exception handler that skips the logged failure, also when it is wrapped
> (such as in the InvocationTargetException of the launcher). Any other
> exception is printed as before. Only when ERROR is logged, so an application
> without logging still sees the failure on stderr.
> _Claude Code on behalf of davsclaus_
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