Codex Cloud Web UI shows an error page when attaching an image file

What version of Codex is running?

codex-web

What subscription do you have?

Pro

Which model were you using?

N/A — this appears to be a web client attachment/upload issue, not a model issue.

What platform is your computer?

macOS

What issue are you seeing?

When using the Codex Cloud Web UI, attaching an image file to a chat causes the web client to show an error page.

This appears to be a frontend/web-client upload or attachment handling bug. The failure happens during the web UI attachment step before the model processes the image.

What steps can reproduce the bug?

1. Open Codex Cloud in the browser.
2. Open any Codex chat/thread.
3. Click the attachment/upload button.
4. Select an image file, such as PNG, JPG, JPEG, or WebP.
5. Observe that the web client shows an error page after attaching the image.

What is the expected behavior?

The image should attach successfully and appear in the chat composer or thread preview.

What is the actual behavior?

The web client renders an error page immediately after attaching the image file.

Impact

This blocks attaching screenshots/images to Codex Cloud chats, which is important for bug reports, UI implementation tasks, visual debugging, design handoffs, and screenshot-based context.

Additional information

• Browser: Chrome
• OS: macOS
• Codex surface: Codex Cloud Web UI
• File type: image file
• File size: [add file size]
• Error page text/code: [paste error text if available]

This is not related to image generation or model behavior.