API Error Message: Coding session not found

Here's a step-by-step troubleshooting checklist for resolving your QuantConnect Local Platform + VSCode errors:

QuantConnect Local Platform + VSCode Troubleshooting Checklist

For errors:

• "API Error Message: Coding session not found." (when opening a project)
• "API Error Message: Code source id is a required parameter" (when closing a project)

1. Confirm Local Platform & CLI Compatibility

1. Check your installed LEAN CLI version:

   lean --version
   

2. If outdated, update the CLI:

   pip install --upgrade lean
   

3. Update Docker images used by the platform:

   lean update
   

4. Restart the CLI and verify the version again.

2. Validate API Credentials

1. Find your credential file:
   • Linux/macOS: ~/.quantconnect/credential.json
   • Windows: %USERPROFILE%\.quantconnect\credential.json
2. Ensure it contains valid and current values:

   {
       "user-id": "<integer>",
       "api-token": "<key>",
       "organization-id": "<guid>"
   }
   

3. Alternatively, check environment variables: QC_USER_ID, QC_API_TOKEN, QC_ORGANIZATION_ID
4. Test credentials:

   lean cloud organizations list
   

   (Should return without authentication errors.)

3. Inspect Project Configuration Files

1. Open .quantconnect/project.json inside your project.
2. Ensure these fields exist and are not empty:
   • "codingSessionId": "<guid>"
   • "codeSourceId": "<guid>"
3. If missing or invalid:
   • Back up project.json.
   • Copy valid IDs from a working project or delete those fields (they may regenerate on next sync).
4. Save and reopen your project in VSCode.

4. Restart the Entire Stack

1. Close VSCode windows.
2. Stop running Docker containers:

   docker ps
   docker stop <containerIds>
   

3. Quit/restart Docker Desktop and wait until it says “Running”.
4. Re-open VSCode and your QuantConnect project.

5. Isolate the Problem

1. Create a new project:

   lean create "troubleshoot_dummy"
   

2. Open it in VSCode.
3. Open, close, and run a quick backtest.
   • If this works, your issue is project-specific (review Step 3).
   • If errors persist, continue.

6. Gather Additional Logs

1. In VSCode: View ➔ Output ➔ choose “QuantConnect” or “Lean”.
2. Use verbose CLI logs:

   lean --log-level=debug cloud push
   

3. Docker logs:

   docker logs <containerId>
   

4. Save all logs for support.

7. Contact QuantConnect Support / Community Include:

• OS and version
• VSCode + QuantConnect extension version
• LEAN CLI version
• Docker Desktop version
• Full error messages/timestamps
• Example project.json (redact IDs)
• Steps already tried (1–6)

Following these steps will help identify and resolve your issue, or prepare you to get fast help from QuantConnect support.

Sources: Debugging - QuantConnect.com, Autocomplete - QuantConnect.com, Debugging Tools - QuantConnect.com, Getting Started - QuantConnect.com, QuantConnect Paper Trading - QuantConnect.com

This is helpful, thx

I'm hitting the same problem(things just stopped working)

+1, I meeting the same issue, i can't found any solution until now