Invalid debug adapter when setting "justMyCode": false

[zone-coba]

Scenario: debugging Python application running in Docker on remote host.

Debugging own code works fine. But as soon we set "justMyCode": false, in order to debug into 3rd party libs code, we get an error:

[error] Invalid debug adapter: Error: Invalid debug adapter

Cannot debug at all, container is running and listening at port, but not accessible.

Turning back to "justMyCode": true, debugging works again, but limited to application code.

Path mappings are triple-checked.

Steps to Reproduce

1. Open VS Code.

2. Set up the launch.json as follows:

   {
       "configurations": [
           // Docker-specific configurations (require Python & Docker extension)
           {
               "name": "Python Debugger: LM Service (in Docker)",
               "type": "docker",
               "request": "launch",
               "preLaunchTask": "docker-run: debug",
               "python": {
                   "pathMappings": [
                       {
                           // our custom code
                           "localRoot": "${workspaceFolder}",
                           "remoteRoot": "/app" // Corresponding path in Docker container
                       },
                       {
                           // 3rd-party libraries code (relevant when "justMyCode": false)
                           "localRoot": "${workspaceFolder}/.venv/lib/python3.12/site-packages/",
                           "remoteRoot": "/app/.venv/lib/python3.12/site-packages/" // Corresponding path in Docker container
                       }
                   ],
                   "projectType": "general",
                   "justMyCode": false, // <=== fails when set to false, fine for true
                   "subProcess": true,
                   "logToFile": true  // Enable verbose logging
               }
           }
       ]
   }

3. Start the debugger.

4. Observe the error message: [error] Error: Invalid debug adapter at vVt.p...

Expected Behavior

The debugger should start successfully with justMyCode set to false.

Versions

vscode is 1.96.2, involved extensions

• Python extension 2024.22.2
• Python Debugger extension 2024.14.0
• Docker extension 1.29.3
• Remote extension suite

all latest versions (as of today 10 JAN 2025)

Same behavior in Py 3.11 and 3.12.

Log

2025-01-10 12:07:56.778 [error] Invalid debug adapter: Error: Invalid debug adapter
    at vVt.p (vscode-file://vscode-app/c:/Users/bell/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:748:95)
    at vVt.$acceptDAExit (vscode-file://vscode-app/c:/Users/bell/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:748:35)
    at Odt.S (vscode-file://vscode-app/c:/Users/bell/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:3144:41680)
    at Odt.Q (vscode-file://vscode-app/c:/Users/bell/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:3144:41458)
    at Odt.M (vscode-file://vscode-app/c:/Users/bell/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:3144:40546)
    at Odt.L (vscode-file://vscode-app/c:/Users/bell/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:3144:39783)
    at oee.value (vscode-file://vscode-app/c:/Users/bell/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:3144:38444)
    at x.B (vscode-file://vscode-app/c:/Users/bell/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:30:748)
    at x.fire (vscode-file://vscode-app/c:/Users/bell/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:30:967)
    at K6.fire (vscode-file://vscode-app/c:/Users/bell/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:762:10348)

[rchiodo]

I don't think this would be a debugpy problem. VS code is for some reason not recognizing the debug adapter handle it launched.

See this code here:
https://github.com/microsoft/vscode/blob/4ccc274b699c0571d051e1000724f8cc7a8548ef/src/vs/workbench/api/browser/mainThreadDebugService.ts#L407

There might be other information in other logs though.

I recommend turning on logging for debugpy and see if you get any more information:
https://github.com/microsoft/debugpy/wiki/Enable-debugger-logs

[zone-coba]

I guess you are right.

Nothing substantial in the logs. But what I can see in Call Stack

1. when "justMyCode": true

CALL STACK                    Running
MainThread                    RUNNING
asyncio_0                     RUNNING

2. when "justMyCode": false

CALL STACK   [Errno 2] No such file or directory: "/home/non-root/.local‘
_joinrealpath   posixpath.py (462:18)
realpath        posixpath.py (427:1)
_run_code       runpy.py (88:1)
_run_module_as_main    runpy.py (198:1)

non-root is the identity the Docker container is running internally. This user doesn't exist on the host system. I guess /home/non-root/.local is where the source code is expected to be outside of the container. But this folder doesn't exist on the host system either since this user is just a "container-internal" one.

Might be an issue with the Docker extension?

[zone-coba]

When I try to debug the Python code on the remote host without Docker, I see something similar in Call Stack when "justMyCode": false:

CALL STACK   [Errno 2]  No such file or directory: runner
isfile                genericpath.py (30:14)
_run_code             runpy.py (88:1)
_run_module_as_main   runpy.py (198;1)

In this case runner is the command which is executed in launch.json.

Hm, confusing. Might be an issue with Remote extension rather than Docker or Python Debug extension?

[rchiodo]

If you're getting a callstack, does that mean it's working? I'm confused as I thought you couldn't even start debugging.

Those errors on the callstack are expected when the source can't be found, but they shouldn't prevent anything except the callstack from working. Debugging should still work.

[zone-coba]

Sorry, I wasn't precise. Debugger hit "Raised Exceptions" when iterating over file path candidates, so obviously working. I did a clean setup of the remote host from scratch, reinstalled all extensions. And ... remote debugging finally works. But honestly I have no clue why. Again, very sorry. Many thanks for your helpful responses.