Error while debugging.

[STofone]

version:2.0.0a4

2025-06-25 15:25:52.523 [info] config modified, restarting server...
2025-06-25 15:25:52.523 [info] cwd: 'e:\ProgSpace\pygls-main/examples/servers'
2025-06-25 15:25:52.523 [info] server: 'code_lens.py'
2025-06-25 15:25:52.523 [info] Looking for environment in which to execute: 'file:///e%3A/ProgSpace/pygls-main/examples/servers/code_lens.py'
2025-06-25 15:25:52.523 [info] Found environment: E:\PROGSPACE\PYGLS-MAIN\.VENV\SCRIPTS\PYTHON.EXE: e:\ProgSpace\pygls-main\.venv\Scripts\python.exe
2025-06-25 15:25:52.523 [info] client options: {
  "documentSelector": [
    {
      "scheme": "file",
      "language": "plaintext"
    }
  ],
  "outputChannel": {
    "name": "pygls",
    "logLevel": 3
  },
  "connectionOptions": {
    "maxRestartCount": 0
  }
}
2025-06-25 15:25:52.566 [info] e:\ProgSpace\pygls-main\.venv\Scripts\python.exe: can't find '__main__' module in 'e:\\ProgSpace\\pygls-main\\examples\\servers'

2025-06-25 15:25:52.571 [info] [Error - 3:25:52 PM] Server initialization failed.
2025-06-25 15:25:52.571 [info]   Message: Pending response rejected since connection got disposed
  Code: -32097 
2025-06-25 15:25:52.571 [info] [Error - 3:25:52 PM] The pygls server crashed 1 times in the last 3 minutes. The server will not be restarted. See the output for more information.
2025-06-25 15:25:52.571 [info] [Error - 3:25:52 PM] pygls client: couldn't create connection to server.
2025-06-25 15:25:52.571 [info]   Message: Pending response rejected since connection got disposed
  Code: -32097 

It works well without debug enable.

Here's my settings.json

{
    "[plaintext]": {
        // Uncomment to enable `textDocument/onTypeFormatting` requests
        // "editor.formatOnType": true
    },
    // Uncomment to override Python interpreter used.
    // "pygls.server.pythonPath": "/path/to/python",
    "pygls.server.debug": true, // This is relative to `pygls.server.cwd`
    "pygls.server.debugHost": "127.0.0.1",
    "pygls.server.cwd": "${workspaceFolder}/examples/servers",
    "pygls.trace.server": "off",
    "pygls.client.documentSelector": [
        {
            "scheme": "file",
            "language": "plaintext"
        }
    ],
    "python.testing.pytestArgs": [
        "."
    ],
    "python.testing.unittestEnabled": false,
    "python.testing.pytestEnabled": true,
    // "pygls.jsonServer.exampleConfiguration": "some value here",
    "pygls.server.launchScript": "code_lens.py",
}

[tombh]

The error seems to be this line: e:\ProgSpace\pygls-main\.venv\Scripts\python.exe: can't find '__main__' module in 'e:\\ProgSpace\\pygls-main\\examples\\servers'.

So you're saying that when you set, "pygls.server.debug": false, to false in your settings.json, then it works as normal?

[STofone]

The error seems to be this line: e:\ProgSpace\pygls-main\.venv\Scripts\python.exe: can't find '__main__' module in 'e:\\ProgSpace\\pygls-main\\examples\\servers'.

So you're saying that when you set, "pygls.server.debug": false, to false in your settings.json, then it works as normal?

Yes.

[tombh]

I'm having trouble getting the playground to work. I think @alcarney might know more.

Just for reference I'm getting Cannot activate extension because ./out/extension.js not found. from the pygls-playground extension.

[alcarney]

The error message looks like the extension is trying to execute the examples folder, rather than the code_lens.py script within it.

$ python examples/servers/
/home/vscode/.local/bin/python: can't find '__main__' module in '/workspaces/main/examples/servers/'

However, I really struggle to come up with a reason why it could be doing that... especially when it only seems to happen with debug set to true. It also doesn't help that I can't reproduce this issue on my machine (though I am running Linux).

You could try increasing the logging level of the output channel to debug, it won't give us much more information, but it will reveal the Python command the extension is trying to execute - minus the path to the server. As an example, this is what I see when debug is set to true

[debug] python: /home/vscode/.cache/pypoetry/virtualenvs/pygls-P8SXPjcW-py3.13/bin/python -Xfrozen_modules=off /home/vscode/.vscode-server/extensions/ms-python.debugpy-2025.8.0/bundled/libs/debugpy --listen localhost:5678 --wait-for-client

Though I'm sure sure if it's going to help much.

Here is the relevant code in the extension

    const cwd = getCwd()
    const serverPath = getServerPath()

    logger.info(`cwd: '${cwd}'`)
    logger.info(`server: '${serverPath}'`)

    const resource = vscode.Uri.joinPath(vscode.Uri.file(cwd), serverPath)
    const pythonCommand = await getPythonCommand(resource)
    if (!pythonCommand) {
        clientStarting = false
        return
    }

    logger.debug(`python: ${pythonCommand.join(" ")}`)
    const serverOptions: ServerOptions = {
        command: pythonCommand[0],
        args: [...pythonCommand.slice(1), serverPath],
        options: { cwd },
    };

Note that serverPath is both logged and included in the args we assign to the ServerOptions object. And from the logs you've provided we can see that it's set correctly

2025-06-25 15:25:52.523 [info] server: 'code_lens.py'

So... all that is to say, I don't really know what could be wrong at this point! 😅

---

Just for reference I'm getting Cannot activate extension because ./out/extension.js not found. from the pygls-playground extension.

@tombh have you run npm install and npm run compile from the .vscode/extensions/pygls-playground folder to setup the extension?

[tombh]

Damn yes the npm run compile step was what I was missing. Which you very clearly have in the docs! Sorry 🙈

[STofone]

@alcarney debug log:

2025-06-30 10:45:03.131 [debug] python: e:\ProgSpace\pygls-main\.venv\Scripts\python.exe -Xfrozen_modules=off  --listen 127.0.0.1:5678 --wait-for-client

[alcarney]

@alcarney debug log:

2025-06-30 10:45:03.131 [debug] python: e:\ProgSpace\pygls-main\.venv\Scripts\python.exe -Xfrozen_modules=off  --listen 127.0.0.1:5678 --wait-for-client

Thanks, unfortunately, it's exactly what I was expecting to see.

Until I can figure out how to reproduce your issue, I don't think I'm going to be able to figure out what is wrong :/