Windows Codex local tool host exits during handshake after update

[985924401peng-lab]

What version of the Codex App are you using (From “About Codex” dialog)?

Powered by Codex & OWL 版本 26.820.80927

What subscription do you have?

plus

What platform is your computer?

Microsoft Windows NT 10.0.19045.0 x64

What issue are you seeing?

I am using the Microsoft Store version of the ChatGPT/Codex Windows app.

App package:
OpenAI.Codex 26.820.9563.0 x64
SignatureKind: Store

Workspace dependencies:
26.826.11250

Every local tool command fails before execution with:

code-mode host exited during handshake

Minimal reproduction:

1. Open a Codex task.
2. Ask Codex to run PowerShell command: Get-Location
3. The command never starts and the handshake error is returned.

The issue started after a recent Codex update.

Troubleshooting already completed:

• Fully exited all ChatGPT/Codex processes
• Rebooted Windows multiple times
• Repaired the Windows app
• Diagnosed the workspace dependencies; diagnostics reported no problem
• Reinstalled the workspace dependencies
• Uninstalled and reinstalled the Microsoft Store ChatGPT app
• Renamed the existing C:\Users\Lenovo.codex directory and tested with a newly created clean profile
• Checked Windows Security protection history; no Codex/OpenAI process was blocked

The problem still occurs with a clean profile and clean reinstall.

Expected result:
Get-Location should return the current PowerShell working directory.

Actual result:
code-mode host exited during handshake

What steps can reproduce the bug?

Feedback ID: no-active-thread-01a045fd-1e2e-7673-be59-cc9d6fff1b92

What is the expected behavior?

Please fix it

Additional information

my ID : no-active-thread-01a045fd-1e2e-7673-be59-cc9d6fff1b92

[github-actions]

Potential duplicates detected. Please review them and close your issue if it is a duplicate.

• [Windows] All Codex tool calls fail with “code-mode host exited during handshake” #41034
• The Codex desktop app's execution service (codex-code-mode-host.exe) exits during handshake, so every exec tool call fails. The error is intermittent but frequent.bug #40899
• [Windows][26.820.7780.0] Local execution fails to start after updating Codex Desktop #41088
• code-mode host exited during handshake; the 5.6 model is not working properly #41049

Powered by Codex Action

[zhangquan920]

I’m experiencing the same issue.

[xiaomin8233-glitch]

Additional Windows desktop reproduction for the local tool host handshake failure.

Environment:

• Codex Desktop package: OpenAI.Codex_26.825.3734.0_x64__2p2nqsd0c76g0
• Codex CLI: codex-cli 0.150.0-alpha.12.2
• OS shell used by the desktop task: Windows PowerShell
• Affected model path: gpt-5.6-sol in Codex Desktop local tasks

Observed behavior:

• In Codex Desktop, a fresh local project task using gpt-5.6-sol fails to run even a minimal command: Get-Location.
• The tool call returns: code-mode host exited during handshake / local command host exits during handshake.
• Repeating the same minimal test in an older existing project task also fails with the same handshake error.

Controls:

• The same local project task using gpt-5.5 can execute Get-Location successfully.
• Direct CLI execution with codex exec --model gpt-5.6-sol ... can execute Get-Location successfully.
• Therefore this does not appear to be a general account/model availability issue or a project/Python/script issue; it appears specific to the Codex Desktop 5.6 Code Mode/local tool host path.

Mitigations attempted:

• Moved codex-primary-runtime and stale codex-runtime-install-* directories out of C:\Users\<user>\.cache\codex-runtimes to force runtime restaging. CLI 5.6 still works, but Desktop 5.6 local tool execution still fails.
• Temporarily changed service_tier from default to priority: no change; reverted.
• Temporarily changed [features] js_repl from false to true: no change; reverted.
• Fresh 5.6 Sol desktop task after these checks still fails on Get-Location.

Current workaround:

• Use gpt-5.5 for local desktop command/file execution tasks.
• Use gpt-5.6-sol only for non-tool reasoning or via CLI until the desktop Code Mode host path is fixed.

[xiuql-a11y]

I’m seeing the same issue on Windows with GPT-5.6 Sol.

Environment:

• Codex Desktop: 26.825.3734.0
• Windows app package: OpenAI.Codex_26.825.3734.0_x64
• Model: gpt-5.6-sol
• Reasoning effort tested: xhigh and other settings
• Windows sandbox config: [windows] sandbox = "unelevated"
• Project: empty/minimal trusted local directory

Symptom:

• Any minimal local command or file read under GPT-5.6 Sol fails before execution with:
  code-mode host exited during handshake
• The same machine, same project, and same Codex installation work normally with GPT-5.5.
• Example minimal test: reading a simple local text file fails under GPT-5.6 Sol before command execution, but succeeds under GPT-5.5.

Troubleshooting already attempted:

• Fully quit Codex, restarted Windows, restarted Codex process.
• Reinstalled/repaired Codex Desktop.
• Renamed/backed up runtime cache and allowed Codex to rebuild runtime.
• Checked Windows Reliability Monitor and Event Viewer.
• Windows Security protection history showed no recent quarantine/block event.
• Checked project ownership; current project owner matches the Windows user.
• .agents does not exist in the minimal test project, so the known .agents ownership workaround does not apply.
• Confirmed sandbox = "unelevated" was already set; this does not resolve the issue.
• Manually launching the code-mode host binary appears to work, which suggests the failure occurs during GPT-5.6 Sol integration/handshake rather than from the binary being missing or immediately blocked.
• Temporarily tested removing GPT-5.6 Sol’s code_mode_only marker from the local model cache and making the cache read-only. This did not provide a valid fix and was reverted.

Conclusion:
This looks model-specific: GPT-5.6 Sol fails during Windows code-mode/sandbox handshake, while GPT-5.5 works in the same environment. Please investigate the GPT-5.6 Sol Windows code-mode integration path and provide either a fixed Codex build/model config or an official workaround.

[xiaomin8233-glitch]

Follow-up reproduction after updating Codex Desktop.

Environment now tested:

• Codex Desktop package: OpenAI.Codex_26.825.4187.0_x64__2p2nqsd0c76g0
• Codex CLI: codex-cli 0.150.0-alpha.12.2
• Windows PowerShell local command smoke test: Get-Location

Result after update:

• gpt-5.6-sol via direct CLI can execute Get-Location successfully.
• A fresh Codex Desktop local project task using gpt-5.6-sol still fails to execute Get-Location.
• The failure remains: code-mode host exited during handshake / local command host exits during handshake before the command runs.
• A fresh Codex Desktop local project task using gpt-5.5 executes the exact same command successfully.

This remains a blocker for using GPT-5.6 Sol for local desktop coding work on Windows, because any file/command/tool workflow fails before first command execution. Please prioritize investigation of the Codex Desktop 5.6 Code Mode host path on Windows.

Prior local mitigations already tried and reverted when ineffective:

• Runtime cache restaging (codex-primary-runtime and stale install dirs moved aside)
• service_tier = "priority"
• [features] js_repl = true

Current workaround remains: use gpt-5.5 for Codex Desktop local command/file execution, or use gpt-5.6-sol via CLI only.

[xiaomin8233-glitch]

Customer escalation / priority request:

This issue is still blocking day-to-day local coding work on Windows. The user relies on Codex Desktop for local project execution, but GPT-5.6 Sol cannot run even the minimal Get-Location command in a fresh desktop task.

The key A/B result remains:

• Codex Desktop + gpt-5.6-sol: local command execution fails before the command runs with code-mode host exited during handshake.
• Codex Desktop + gpt-5.5: the exact same local command succeeds.
• Codex CLI + gpt-5.6-sol: the exact same local command succeeds.

This makes the problem very likely specific to the Windows Codex Desktop 5.6 local Code Mode host path, not the project, shell, account, or model availability in general.

Please prioritize this fix. The practical impact is that users cannot use GPT-5.6 Sol for local file/command/edit workflows in Codex Desktop and must downgrade to GPT-5.5 for any real local execution work.

[xiaomin8233-glitch]

Additional note from the affected user:

The user is not comfortable operating the in-app / feedback flow and has asked us to route the report through this GitHub issue instead. Please treat the reproduction details above as the active customer report.

The blocker remains: on Windows Codex Desktop, gpt-5.6-sol cannot execute local commands because the local Code Mode host exits during handshake, while gpt-5.5 works in Desktop and gpt-5.6-sol works via CLI.

Please prioritize a Desktop-side fix or provide a recommended workaround that restores GPT-5.6 Sol local command/file execution in Codex Desktop.