Debugger: Failed to send request to LSP proxy

[sedax90]

Relevance Confirmation

• I confirmed that this is not an issue with the Eclipse JDT Language Server itself

What happened?

I've a task configured for debug:

  {
    "label": "Attach to Java app",
    "adapter": "Java",
    "request": "attach",
    "hostName": "localhost",
    "port": 5005,
  },

But when I lauch this it stops immediatly with:

error: "Failed to start debug session: Failed to start debug session via LSP: Failed to send request to LSP proxy: error sending request for url (http://localhost:33871/)\n\nCaused by:\n    0: client error (Connect)\n    1: tcp connect error\n    2: Connection refused (os error 111)"

What did you expect to happen?

Debugger should attach to current running Java application like vscode.

Environment

Zed: 0.227.1
Platform: Ubuntu 25.04
Java: Amazon Corretto 21

[tartarughina]

@sedax90 is the issue reproducible consistently or is this affecting only a single project?

Otherwise, if you're willing to become a beta tester, would you try out a new proxy I've been working on?

Compared to the one currently available, it is written in Rust and if the issue is not reproducible there I'll prioritize its release.

To install it

1. Clone my personal repo https://github.com/tartarughina/java
2. Switch to branch rust-proxy
3. From zed install a dev extension selecting providing the path to the repo
4. It is expected to fail, as it will try to retrieve the proxy from GitHub
5. Run just proxy-install to make the proxy available

[sedax90]

@sedax90 is the issue reproducible consistently or is this affecting only a single project?

Otherwise, if you're willing to become a beta tester, would you try out a new proxy I've been working on?

Compared to the one currently available, it is written in Rust and if the issue is not reproducible there I'll prioritize its release.

To install it

1. Clone my personal repo https://github.com/tartarughina/java
2. Switch to branch rust-proxy
3. From zed install a dev extension selecting providing the path to the repo
4. It is expected to fail, as it will try to retrieve the proxy from GitHub
5. Run just proxy-install to make the proxy available

It's reproducible on every project with my gradle + zed config.

I'm happy to try you repo, I'm stuck at point 5:

 just proxy-install
cd proxy && cargo build --release --target x86_64-unknown-linux-gnu
error: failed to parse manifest at `/home/cristian/Downloads/java/Cargo.toml`

Caused by:
  feature `edition2024` is required

  The package requires the Cargo feature called `edition2024`, but that feature is not stabilized in this version of Cargo (1.80.1 (376290515 2024-07-16)).
  Consider trying a newer version of Cargo (this may require the nightly release).
  See https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#edition-2024 for more information about the status of this feature.
error: Recipe `proxy-release` failed on line 19 with exit code 101

sorry but I'm new with rust...

[tartarughina]

You need to update Rust to the latest version. That should be enough to unblock you

[sedax90]

ok now it's working, I've to maintain the java extension installed with also your dev extension?

[tartarughina]

The dev extension is going to override the one you installed via the Marketplace

[sedax90]

ok, I confirm that's overriding the original dev, now the error during the debug attach is different:

error: "Debugger plugin is not loaded"

[tartarughina]

Check if the JAR file for the debugger is available on the system