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The Codex VS Code extension says “Codex could not start” because, according to community reports, version 26.1021.22027 (released around Oct 23, 2026) makes the webview miss a 30-second ready timeout.
Downgrade to 26.1007.21434 to fix this reported startup regression.
No fixed release was available on Marketplace as of Oct 28, 2026.
Community reports describe a startup regression in the OpenAI Codex extension 26.1021.22027, released around Oct 23, 2026.
Version 26.1007.21434 is the reported working workaround.
No fixed Marketplace release was reported as of Oct 28, 2026, and issues #56655 and #56691 remained open.
Downgrade the Codex extension to 26.1007.21434 and reload VS Code to apply the reported workaround.
Disabling and re-enabling the Codex extension works for some users. Open the Extensions view in VS Code, find the OpenAI Codex extension, and use its gear menu to disable it. Re-enable it and try opening Codex again.
Install version 26.1007.21434 explicitly with the following command in a terminal where the VS Code code command is available:
code --install-extension [email protected] --forceThen run Developer: Reload Window from the Command Palette. Reinstalling from the extension menu reportedly does not help; choose the older version explicitly.
Choose the older version using Install Specific Version in the extension’s gear menu.
Open Extensions → gear on the OpenAI ChatGPT/Codex extension → Install Specific Version → 26.1007.21434. Reload the window if prompted. This is the GUI alternative to the command above.
Open the extension’s gear menu and uncheck Auto Update so the affected version is not installed again.
Not recommended: turning off auto-update globally in VS Code settings stops updates for all extensions, not just the Codex extension.
Re-enable auto-update when the linked issues close and a fixed release is available.
Version 26.1007.21434 is the reported working version for this startup regression in the dated community reports.
Not recommended: patching the 30-second timer in the extension bundle. Updates overwrite the patch; downgrading is the reported workaround.
It means the Codex VS Code webview did not become ready within the extension’s 30-second ready limit.
According to GitHub user jumincho’s analysis, both versions have the same 30-second ready limit. The webview grew from 539 MB / 19,524 files to 723 MB / 22,544 files.
Roughly 3,045 JavaScript modules, together with a preload loop, block the main thread for 33 seconds or more. The interface misses the ready deadline before it can respond.
Slower machines and heavier system load make the timeout more likely. Reports also reproduce it in dev containers. This is a community diagnosis, rather than an official root-cause statement.
Install 26.1007.21434 in the environment where the OpenAI Codex extension is installed, then reload that VS Code window.
Use the downgrade steps above. If startup still fails, check the CODEX_CLI_PATH environment variable: an override pointing to an old codex.exe can launch an outdated CLI. Remove or correct the override, then restart VS Code so it picks up the environment change.
Use Install Specific Version, or the terminal command if code is on your PATH. If the command is unavailable, use the Command Palette’s Shell Command: Install 'code' command in PATH, or use the GUI. Reload the window after downgrading.
Downgrade the extension in the environment where it is installed, then reload that window.
Ubuntu — unconfirmed: upgrading VS Code to 1.143.2 may help. Treat this as an unconfirmed report, not a replacement for the downgrade workaround.
Downgrade the extension in the environment where it is installed, then reload that window.
In a Remote-SSH window, check the remote Extensions view as well as the local installation. Dev containers can reproduce this timeout too.
Use the general downgrade steps in the relevant WSL window; this workaround has not been specifically tested in WSL.
For these general steps, open the relevant WSL window, check where the extension is installed, select 26.1007.21434 in that Extensions view, and reload the window. Keep the auto-update setting scoped to the extension.
Confirm the installed version and reload VS Code; on Windows, also check for a CODEX_CLI_PATH override.
Confirm that version 26.1007.21434 is installed, then run Developer: Reload Window in VS Code. On Windows, check whether CODEX_CLI_PATH points to an old codex.exe; remove or correct the override and restart VS Code.
These are likely different problems. For CLI 0.163 or later, try the command below, or /daemon in the TUI to manage or restart the daemon. These steps are separate from the extension webview workaround.
codex app-server daemon restartReinstalling from the menu reportedly does not help. Select version 26.1007.21434 explicitly, using the CLI command or Install Specific Version.
No fixed Marketplace release was reported as of October 28, 2026. Follow #56655 and #56691 for a confirmed fix, then re-enable auto-update when those issues close and the fixed version is available.
Reinstalling from the menu reportedly does not help this regression; explicitly select version 26.1007.21434 and reload VS Code.
On Windows, a CODEX_CLI_PATH override pointing to an old codex.exe can launch an outdated CLI; remove or correct the override and restart VS Code.
The extension has a 30-second ready limit, and community analysis reports that the webview blocks the main thread for 33 seconds or more, missing that deadline.
On 26.1021.22027, the webview often needs 20-29 seconds to load, close to the 30-second ready limit, so it sometimes opens slowly and sometimes fails with Codex could not start. See the timeout section for details. Downgrade to 26.1007.21434 to fix this startup regression.
The Codex CLI is an option while the extension issue remains unresolved, since the reported bug is in the extension webview. Whether to use it depends on your preferred workflow.
The linked GitHub issues and CodexUpdate community post support this version-specific workaround and analysis. Availability statements above are dated; check the issues before updating.