PowerShell Shell Sessions Dying Silently

[39otsu]

Describe the bug

GitHub Copilot CLI 0.0.411-1
Windows_NT
Copilot CLI 0.0.411-1
Python 3.14

Affected version

GitHub Copilot CLI 0.0.411-1

Steps to reproduce the behavior

1. Start a Copilot CLI session.
2. Execute any powershell tool call (sync or async mode).
3. The tool returns a shellId and reports the command is "still running after N seconds."
4. Call read_powershell with the returned shellId.
5. Response: "Invalid shell ID: <id>. Please supply a valid shell ID to read output from." and "<no active shell sessions>".

Expected behavior

Shell sessions should remain alive and readable for the duration of the command execution, or at minimum return output before dying.

Additional context

• Every shell session dies between the powershell invocation and the subsequent read_powershell call.
• This occurs regardless of:
  • Command complexity: Fails on echo "hello", Write-Output "test", Get-Content, python -c "...", python script.py, Test-Path.
  • Mode: Both mode="sync" and mode="async" produce the same result.
  • Wait time: initial_wait values of 30, 45, 60, 90, 120, 180, and 300 seconds all fail identically.
  • Shell ID format: Auto-generated numeric IDs (8 through 19) and custom string IDs (sdk-check, test-shell) all fail.
• Shell sessions did work earlier in this same session such as the initial pip install, YAML loading verification, py_compile checks, and output manager tests all completed successfully with output.
• The failure started occurring consistently after approximately 14 successful shell invocations.

Shell IDs That Failed (in order)

Shell ID	Command	Result
8	python main.py (first full run)	Produced partial output, then session died on read_powershell
9	python -c "..." (SDK debug)	No output, session died
10	python -u -c "..." (SDK debug)	No output, session died
11	python -u -c "import copilot..."	No output, session died
12	python -m pip show github-copilot-sdk	No output, session died
sdk-check	python -m pip show github-copilot-sdk	No output, session died
13	python _debug_sdk.py	No output, session died
14	Remove-Item ...	No output, session died
15	python main.py (second run)	No output, session died
16	python main.py > file 2>&1	No output, session died
17	Get-Content file	No output, session died
18	Test-Path file	No output, session died
19	echo "hello"	No output, session died

• Cannot run, test, or verify any code changes.
• Cannot execute any CLI commands (build, test, install, run).
• Effectively blocks all tool-assisted development work for the remainder of the session.
• The view, create, edit, and grep/glob file tools continued working throughout, only PowerShell sessions were affected.

[jzebedee]

This happens with any Windows sessions, regardless of the shell used. The same behavior is seen when running Copilot CLI from PowerShell, pwsh, cmd, or git bash.

[16hex-Dumb]

When the PATH environment variable was modified or misconfigured, GitHub Copilot CLI would exhibit similar errors: shell sessions being terminated, “Invalid shell ID”, or “no active shell sessions”.

After restoring PATH to a correct configuration—including Git Bash, PowerShell, Scoop, and Conda—the Copilot CLI commands executed normally again.

This suggests that the bug is likely related to abnormal PATH environment settings, which can prevent shells from starting properly or cause shell sessions to be interrupted.

[MRayermannMSFT]

@39otsu can you install CLI version 0.0.412-2 and see if this still repros for you?

[MRayermannMSFT]

Bah, didn't see new comments until after I refreshed. @16hex-Dumb , @jzebedee same as well, check version 0.0.412-2? 😄

[jzebedee]

Bah, didn't see new comments until after I refreshed. @16hex-Dumb , @jzebedee same as well, check version 0.0.412-2? 😄

No, this issue is still present in both v0.0.412-2 and v0.0.413-0

[MRayermannMSFT]

@jzebedee assuming you are reproducing that consistently, can you do the following for me:

1. Install Copilot CLI 0.0.413 or later (copilot update to get latest)
2. Run copilot with flag --log-interactive-shells
3. Run a simple prompt that repros the issue, like "run echo hello using your powershell tool" (model doesn't matter, use a 0x if you'd like)
4. Use /session
5. Open parent directory of the Session: file in your file browser/explorer
6. Look for a shell-logs/ folder
7. There should be a single file in it, drag and drop here (feel free to look inside before uploading if you wish)

Thanks!

[jzebedee]

Yes, this issue is consistent.

shell-0-1771730020447.log

[jzebedee]

This may not be Windows-specific either, since #1146 / #1173 has it happening since January (December for #755) on Linux hosts as well.

[MRayermannMSFT]

@jzebedee thank you so much for those logs. I've used to those to (hopefully) implement a fix, and to construct an end to end test based on how ConPTY is behaving on your machine. Can you please:

1. Install latest Copilot, copilot update
2. Run copilot --log-interactive-shells
3. Do the same "run echo hello using your powershell tool" prompt test again
4. Tell me if it works/doesn't work
5. Regardless if it works or does not work, upload the generated shell-logs/ file again.

If it doesn't work, then I'll see what I've missed. If it does work, then there should be more in the log now such that I can implement an even more complete end to end test for your machine's behavior.

Thanks again!

[MRayermannMSFT]

For anyone else with similar issue, please do as I instructed here / here. Thanks!