Can't debug any Java or Kotlin application
I can't seem to get the debugger in IntelliJ to work. When I click the debug button, the program starts and executes normally in the debug window, everything works as expected, except that breakpoints are never triggered. I also don't get any message in the console output that the debugger has connected to the VM which I remember it should show when debugging.
I've created the most simple Java project I could think of by just creating a new Java project via the New Project... action and leaving everything at the defaults, creating a class with literally nothing more than a main method with two print statements in it. Setting a breakpoint on each print statement and debugging the main method does run the program, but does not stop at breakpoints.
What else I've tried:
- Checked that breakpoints are unmuted
- Invalidated caches
- Tried both JRE 1.8 and JRE 10 to run the Debug Configuration
The problem persists on both Windows machines I'm working on, with separate IntelliJ instances, which are linked to my JetBrains Account with Settings Syc activated, which leads me to think it's some weird setting I've changed, but I can't think of what that could be.
Can anyone help me find out what's wrong here?
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How do the breakpoints look like in the editor when debugger is connected? Do they have the checkmarks?
Are you using any custom VM options to run your app?
Any exceptions in idea.log: https://intellij-support.jetbrains.com/hc/articles/207241085 ?
The breakpoints don't change when I start the program, they do not have checkmarks. I suspect the debugger doesn't even connect to the VM, as I also get no corresponding console output stating that the debugger has connected, which I think should be there, right?
I'm not using any custom VM options, it's a plain, newly generated project with no specific run configurations, I just click on the little green arrow to the left of the main method signature.
Nope, no exceptions or other messages that seem relevant to me at quick glance.
Try checking Java Debugger logs for anything suspicious: https://intellij-support.jetbrains.com/hc/en-us/articles/207241125 .
A screencast may also help to spot anything unusual.
You can also try to backup and delete IDE settings (https://intellij-support.jetbrains.com/hc/articles/206544519) to start from scratch, don't import anything and don't sync with the account, set up a JDK from scratch and try to debug again.
Check that you don't have _JAVA_OPTIONS or JAVA_TOOL_OPTIONS environment variables specified that can override IntelliJ IDEA options.
Inspect the command line printed in the IDE console:
Notice the -agentlib:jdwp=transport=dt_socket,address=127.0.0.1:64716,suspend=y,server=n option used to enable the debugger and the Connected to the target VM, address: '127.0.0.1:64716', transport: 'socket' message.
Sorry for taking so long to get back to this. I found nothing in the logs, no special env variables. The command line did not show that option that enabled the debugger.
I did find the culprit, however - on a hunch, I disabled all non-bundled plugins, and hey, I was happily debugging again. One almost-worst-case binary search pass enabling and disabling plugins later, it seems like this particular plugin was causing the problem: https://plugins.jetbrains.com/plugin/7955-pony# I have no idea why, as it should just be some rudimentary support for a language that has nothing to do with java, but hey, I wasn't using it anyways so I just uninstalled it and everything is working again.
Thank you for your suggestions and support!
In my case, clicking run debug wouldn't even start the program. After disabling a few plugins and restarting the IDE, it worked 🤷♂️
David Rekowski It might be helpful to future visitors of this post to mention what plugin was causing the issue for you :)
If I only recalled which one I disabled :-)
Let me see if I can list the ones I think I remember: Database Navigator, Go, Kubernetes and possibly soapUI.
For what it's worth, I don't know if David Rekowski disabled the same plugin as I did, but for me it worked only after disabling the bundled Kotlin plugin (https://plugins.jetbrains.com/plugin/6954-kotlin)
It aligns with this comment from another discussion:
https://intellij-support.jetbrains.com/hc/en-us/community/posts/360000891860-Kotlin-Compile-Error?page=1#community_comment_360000261400
After disabling it, it was possible to execute application in debug mode again.
Capgemini Powrozek To understand and report the issue with the plugin to the developers, could you provide the following details and upload it to https://uploads.jetbrains.com/ the upload_id with us ?
- Idea log zip captured with the Kotlin plugin enabled. You can capture it using Help | Collect Logs and Diagnostic Data…
- Screenshot of run config.
- In case you are able to reproduce this with a sample project please share the reproducer project
This should help us work towards a permanent fix. Thank you!
Hi Abhishek Sah, here it is:
Upload id: 2025_11_17_6jviVpWxLFG4LJ8ZgwBZ2d (file: kotlin plugin enabling logs.txt)
This is an extract from C:\Users\kpowroze\AppData\Local\JetBrains\IntelliJIdea2025.2\log\idea
I got to this path on my local machine through Help | Show log in Explorer. I put in the .txt file only logs that start when I enabled the Kotlin plugin ("Plugins to enable: [org.jetbrains.kotlin]").
Regarding the screenshot of run config, here it is:
Upload id: 2025_11_17_pXu6ABqJLZbV4swsmxRs2y (file: run config.png)
Could you also try to uncheck "Attach coroutine agent" in Settings | Build, Execution, Deployment | Debugger if it helps?
Yes Abhishek Sah, the log is extracted from the path I provided above and it consists of logs right after enabling Kotlin plugin, that's why the first log is “Plugins to enable: [org.jetbrains.kotlin]” and latter logs are until the app failed in debug mode.
As for the checkbox in Settings, I don't have “Attach coroutine agent” as a presentable option under the path you pinpointed, I only have something that sounds similar, which is “”Attach memory agent".