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Codex VS Code extension not working? Roll back and pin it

You updated the Codex extension in VS Code and now it won't open. Instead you get a notification: "Codex could not start. The extension could not start its user interface." As of October 2026, several users in the openai/codex GitHub issues report this after the 26.1021.22027 update, and two of them report that rolling back fixed it for them. This guide covers the rollback and how to stop VS Code from updating it again.

If you want the next step, read Codex desktop “Cannot serialize value” error on new worktree chats: how to fix it.

Quick fix

  • Roll back: in the Extensions view, right-click the Codex extension, choose Install Another Version, and pick 26.1007.21434.
  • Pin it: right-click the extension again and turn off Auto Update for it, so VS Code doesn't reinstall the broken build.
  • Restart extensions when VS Code prompts you.
  • Watch the issue and only update once a fixed build is reported.

What the error looks like

In issue #56655 (opened 24 Oct 2026), the reporter says that after upgrading the extension to v26.51021.22027, "Codex doesn't start", with the notification above. They were on Windows 11 and VS Code 1.143.1.

Other users in the thread report the same failure on Windows 10 and Windows 11 with version 26.1021.22027. One shared an extension log ending in Webview renderer did not become ready with reason=renderer_ready_timeout, after 30 seconds. They also tried a full restart, a separate VS Code user-data directory and disabling other extensions, and the problem stayed. The cause isn't confirmed, and the issue is still open as of October 2026.

Step 1: install the previous version

VS Code's extension docs say: "If you want to install a specific version of an extension, right-click the extension and select Install Another Version. You can then select a version from the available list."

  1. Open the Extensions view (Ctrl+Shift+X on Windows and Linux, Cmd+Shift+X on macOS).
  2. Find the Codex extension. In the issue, its ID shows as openai.chatgpt.
  3. Right-click it and choose Install Another Version.
  4. Pick 26.1007.21434.

One user in the thread wrote: "I downgraded to 26.1007.21434 and it works back again." The original reporter wrote the rollback version as 26.51007.21434, and one commenter noted their installed pre-release build carried an extra 5 (26.51021.22027) while the log showed 26.1021.22027. So the version list may show either form; pick the build ending in 21434 that matches your channel.

Reports aren't unanimous: one commenter says 26.51021.22027 works for them. If the current version opens for you, you don't need to roll back.

Step 2: pin the version by turning off auto-update

If auto-update stays on, VS Code can install the broken build again. The docs say you "can also configure auto update for individual extensions by right-clicking on an extension and toggling the Auto Update item."

To turn off updates for all extensions instead, run Disable Auto Update for Extensions from the Command Palette, or set this in your settings:

"extensions.autoUpdate": false

The docs add that, by default, VS Code waits 12 hours after an update is published before installing it automatically (extensions.autoUpdateDelay), and that administrators can manage these settings through enterprise policies.

Step 3: update again once it’s fixed

With auto-update off, VS Code won't fetch the fix either. The docs describe the Show Extension Updates command for checking manually. Keep an eye on issue #56655, and when users report a working build, select Update on the extension and turn Auto Update back on if you want it.

Be careful with help offers in issue threads

Some comments in public issue threads offer private troubleshooting by email. Don't send logs, tokens or account details to strangers. Stick to the steps in the issue and in official docs.

If you also use the Codex desktop app, see fixing new worktree chats in Codex Desktop.

Sources

As of October 2026 (sources checked 24 Oct 2026):

  • GitHub issue #56655, UI doesn't start in VS Code extension 26.51021.22027: https://github.com/openai/codex/issues/56655
  • VS Code docs, extension marketplace (Install Another Version, auto-update): https://code.visualstudio.com/docs/configure/extensions/extension-marketplace

Codex, ChatGPT and OpenAI, Visual Studio Code and Microsoft, and other names belong to their owners. Names are used only to identify products and compatibility. Stack & Ship is not affiliated with or endorsed by any of them.

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