Sidebar UI fails to start

“Codex could not start its user interface.”

Is this your bug? What gets counted gets fixed. Pile on.

Paste this into your agent. It files your report, with your error and version.

I hit this bug: rapsheet.dev/sheets/codex/issues/20956/file
Follow it to file my report. Show me the text before you send.

No install. No account. Public and anonymous. The link asks your agent for one report, nothing else. What it sends

Fading. 1 report in the last 7 days and 2 the week before. A workaround is known.

Codex sidebar UI fails to start in VS Code on Linux. Sidebar stays on the loading logo, then "Codex could not start its user interface" appears after 30 seconds; app-server initializes but webview never reports ready.

Is this your bug?

File my report

Where: VS Code extension
Error text: [CodexWebviewProvider] Webview renderer did not become ready elapsedMs=30000 extensionVersion=26.1021.22027 reason=renderer_ready_timeout receivedWebviewMessage=false role=sidebar stage=renderer timeoutMs=30000
Versions: 26.1021.22027
Platforms: Linux
How bad: Breaks a normal workflow. Some reports say it blocks them completely.

Part of: Codex VS Code extension shows "Codex could not start" and its sidebar UI never loads9 bugs

Original reports4, newest first

Nov 1, 2026VS Code Extension (26.1021.22027) fails with "Codex could not start its user interface" (renderer_ready_timeout) due to eager modulepreload of 3,203 chunksOn GitHub#58811
Oct 30, 2026[VS Code Extension] v26.1021.22027 fails to start UI on Linux (renderer_ready_timeout due to 3,203 unbundled modulepreload chunks)On GitHub#58398
Oct 29, 2026[VS Code Webview] Linux: UI hangs and fails with "Webview renderer did not become ready" (EMFILE due to massive modulepreload storm of 3,200+ chunks)On GitHub#58099
Oct 24, 2026Linux desktop launch: Codex webview exhausts renderer RLIMIT_NOFILE=1024 (26.1021.22027)On GitHub#56703