Win: After upgrading Codex, I'm getting "windows sandbox: runner error: CreateProcessAsUserW failed: 1920"

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

• #19189
• #20346

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Same issue "windows sandbox: runner error: CreateProcessAsUserW failed: 1920". Windows 10, Powershell 7.6.1

Same issue with Windows 11 25H2, PowerShell 7.6.1 and Codex Desktop 0.128.0.

Adding another Windows data point for this issue.

I am seeing the same sandbox runner failure:

windows sandbox: runner error: CreateProcessAsUserW failed: 1920

In my case it is intermittent rather than a total failure of every command. After restarting Codex Desktop, I ran a small set of sandboxed commands in the same workspace:

• In a parallel batch, rg --files ... succeeded, while Get-Location, Get-ChildItem, and git status --short failed before the command actually executed with the same CreateProcessAsUserW failed: 1920 error.
• Retrying serially, rg --files, git status --short, and Get-Content -Raw README.md succeeded.
• Get-ChildItem ... still failed with CreateProcessAsUserW failed: 1920.
• Running the same kind of diagnostic commands with escalated/non-sandboxed execution works.

So this looks like the same Windows sandbox process-spawn family as this issue and the linked duplicates, but not necessarily a simple "all commands always fail" case. PowerShell/cmdlet launches and concurrent shell starts seem more likely to trigger it, while some direct executables such as rg can still succeed.

The failure happens at the sandbox runner/process creation layer, before user command output is produced.

The same issue can be reproduced in Codex Desktop 26.616.71553. It completely breaks the 'Approve for me' and 'Full Access' functionality, resulting in a terrible user experience!

Adding another Windows/Codex Desktop data point for the same CreateProcessAsUserW failed: 1920 sandbox runner failure.

Environment:

• Codex Desktop package folder: OpenAI.Codex_26.623.4041.0_x64__2p2nqsd0c76g0
• OS context available to this thread: Windows, PowerShell shell, workspace-write sandbox
• Workspace root: C:\Users\arvid\Documents\Codex\2026-06-26\i
• Observed date: 2026-06-26

Observed behaviour:

• Normal sandboxed shell commands fail before PowerShell starts.
• Read-only Get-Content -Path C:\Users\arvid\Documents\Codex\AGENTS.md fails with:

windows sandbox: runner error: CreateProcessAsUserW failed: 1920

• Trivial commands also fail with the same error:
• Get-Location
• Write-Output ok

Recovery attempts:

• Fully closed and reopened Codex Desktop.
• Resumed the thread and retried the same normal sandboxed read.
• The error persisted after restart.

Workaround:

• Running the same read-only command through escalated/non-sandboxed execution succeeds.
• Example: Get-Content -Path C:\Users\arvid\Documents\Codex\AGENTS.md succeeds when run with escalated read-only access.

Duplicate/release-note check before commenting:

• This issue appears to be the exact existing tracker for failed: 1920.
• I also checked recent openai/codex release notes via GitHub release rust-v0.142.2 published 2026-06-25 and did not see this sandbox launch failure called out there.

Still present in the latest Codex Desktop release on this machine.

Observed on:

• Package folder: OpenAI.Codex_26.623.5546.0_x64__2p2nqsd0c76g0
• Date observed: 2026-06-28
• OS context: Windows, Codex Desktop
• Shell context: PowerShell launched through Codex Desktop tooling

Repro evidence from this session:

• A read-only command such as Get-Content -Path "C:\Users\arvid\Documents\Codex\AGENTS.md" failed before PowerShell could execute.
• The failure was:

windows sandbox: runner error: CreateProcessAsUserW failed: 1920

The same command succeeded when retried with the non-sandboxed/escalated workaround, so this still appears to be the sandbox process-launch failure rather than a problem with the PowerShell command or file path.

Still reproducing on the latest Codex Desktop update available to me.

Environment:

• Date: 2026-06-30
• Windows package folder: OpenAI.Codex_26.623.9142.0_x64__2p2nqsd0c76g0
• Shell attempted by Codex: PowerShell

Repro from a fresh Codex Desktop thread:

1. Run a simple sandboxed PowerShell read command, for example:

Get-AppxPackage OpenAI.Codex | Select-Object Name, Version, PackageFullName

1. PowerShell does not start.
2. Codex reports:

windows sandbox: runner error: CreateProcessAsUserW failed: 1920

The same failure happened earlier in the same thread when trying to read an attached text file with Get-Content, before PowerShell could start. Retrying the same read-only command outside the sandbox worked, so this still appears to be the sandbox process-launch failure rather than the target command itself.

One extra note: when run outside the sandbox in this environment, Get-AppxPackage itself could not load the Appx module (Operation is not supported on this platform. (0x80131539)), so I used the installed WindowsApps package folder name above as the version source.

Still reproducing after the latest Codex Desktop update available on this machine.

Environment:

• Date observed: 2026-07-01
• Windows package folder: OpenAI.Codex_26.623.11225.0_x64__2p2nqsd0c76g0
• Shell attempted by Codex: PowerShell
• Sandbox mode/context: workspace-write / managed restricted filesystem

Repro evidence from this session:

1. Codex attempted a read-only attachment inspection:

Get-Content -Path 'C:\Users\arvid\.codex\attachments\29a1da82-ead4-413c-b781-5d745a1ac35f\pasted-text.txt'

1. PowerShell did not start.
2. The tool call failed before command output with:

windows sandbox: runner error: CreateProcessAsUserW failed: 1920

1. Retrying the same read-only inspection outside the sandbox / with escalation succeeded.

I also checked the current upstream state before posting:

• This issue is still open.
• The latest GitHub release I saw is rust-v0.142.5, published 2026-07-01.
• Its release notes mention only the websocket trace logging fix from #30771; I did not see this Windows sandbox process-launch failure called out as fixed.
• Search results still point to this issue as the exact Desktop/CLI tracker, with #30219 tracking the related Codex Extension / VS Code case.

So this still appears to be the same Windows sandbox process-launch failure rather than a problem with the PowerShell command, attachment path, or file permissions.

Resolved this by uninstall the pwsh and install it from https://github.com/PowerShell/PowerShell/releases