No delegateCommandHandler for vscode.java.validateLaunchConfig — unable to launch any Java application #1609

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1. github-actions commented on Feb 17, 2026

   

   github-actionsBot

   on Feb 17, 2026 – with GitHub Actions

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   Hi leotronic (@leo-tronic), I'm an AI Support assistant here to help with your issue. While the team reviews your request, I wanted to provide some possible tips and documentation that might help you in the meantime.

   • This issue is tracked upstream: Adapter descriptor ERROR “No delegateCommandHandler for vscode.java.validateLaunchConfig”
     • URL: Adapter descriptor ERROR "No delegateCommandHandler for vscode.java.validateLaunchConfig" #1448
     • Description: Same error when launching or validating launch.json. No workaround posted yet; you can subscribe there for updates.

   Suggestions to try in the meantime:

   • Verify both “Language Support for Java” (redhat.java) and “Debugger for Java” (vscjava.vscode-java-debug) are activated in your workspace: run Developer: Show Running Extensions and confirm they’re enabled.
   • Ensure the workspace is trusted (untrusted workspaces disable debug APIs).
   • Reinstall the Java Extension Pack, then reload VS Code.
   • Clear extension state: run Java: Clean the Java language server workspace, restart, and check for errors in Output → Language Support for Java.
   • Enable verbose debug logs by adding to your settings:

     "java.trace.server": "verbose"

     then inspect the Debug Console and Developer Tools console for errors.

   Other references with low confidence

   - No delegateCommandHandler for vscode.java.startDebugSession (attach debugger fails) https://github.com//issues/728 - No delegateCommandHandler for vscode.java.resolveMainMethod (error on F5) https://github.com//issues/1342 - No delegateCommandHandler for vscode.java.test.get.testpath / findJavaProjects (Java Test extension) https://github.com/microsoft/vscode-java-test/issues/1681

   The team will respond to your issue shortly. I hope these suggestions are helpful in the meantime. If this comment helped you, please give it a 👍. If the suggestion was not helpful or incorrect, please give it a 👎. Your feedback helps us improve!
2. github-actions

   added

   ai-triaged

   bug

   on Feb 17, 2026
3. leotronic (leo-tronic)

   closed this as not plannedon Feb 17, 2026
4. leo-tronic commented on Feb 18, 2026

   

   leotronic (leo-tronic)

   on Feb 18, 2026

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   I ended up downgrading Java debug versions into it worked. It took a few tries.

   For better devex, it would be an improvement if the newer versions worked out of the box. Maybe a simple integration test to confirm the above Java app runs successfully without errors?