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Rank, 14 days: 2 on the Codex sheet
228 people reported

All time, since Oct 13, including 175 thumbs-up on GitHub.

Codex VS Code extension shows "Codex could not start" and its sidebar UI never loads

“The Codex app-server starts successfully, but the sidebar never becomes ready.”

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Fading. 63 reports and thumbs-up in the last 7 days and 156 the week before.

9 bugs in this theme

  1. Extension UI fails to startHas a workaround128 people
  2. Sidebar renderer_ready_timeoutHas a workaround52 people
  3. User interface fails to startHas a workaround23 people
  4. Sidebar renderer_ready_timeoutHas a workaround18 people
  5. Codex UI fails to start6 people
  6. Sidebar UI fails to startHas a workaround4 people
  7. Sidebar UI fails to startHas a workaround3 people
  8. Webview fails in Remote WSLHas a workaround2 people
  9. Extension UI fails to startNo workaround yet2 people

What's included

  • Panel shows "The extension could not start its user interface" after renderer_ready_timeout with receivedWebviewMessage=false, while the app-server initializes
  • Starts after updating to extension 26.1021.22027 / 26.51021.22027 on Windows; downgrading to 26.1007.21434 restores the UI
  • Remote WSL, Remote-SSH and Dev Containers windows fail; WSL webview assets return HTTP 401 after a VS Code update
  • Linux sidebar stays on the loading logo or freezes, with renderers hitting the 1024 open-file limit during thousands of module preloads
  • Service worker errors such as "Could not register service worker" or "Could not find inner client for request"

Not included

  • Codex panel that loaded fine turning solid grey partway through a conversation
  • Codex CLI or app-server failing to start or authenticate

Original reports53, newest first

  1. Intermittent Codex VS Code UI startup failure on Windows; requires 4–5+ restartsOn GitHub#59943
  2. BugOn GitHub#59876
  3. VS Code extension sidebar never loads — renderer_ready_timeoutOn GitHub#59865
  4. Codex could not startOn GitHub#59857
  5. Codex panel shows "could not start its user interface" on VS Code Insiders + Remote-SSH (renderer_ready_timeout)On GitHub#59840
  6. VS Code Codex sidebar renderer times out after 30 secondsOn GitHub#59625
  7. Codex VS Code extension fails to initialize webview — renderer_ready_timeout on Windows 11On GitHub#59470
  8. [VS Code][Windows] Codex 26.1021.22027 intermittently fails to initialize its sidebar in a clean profileOn GitHub#59425
  9. codex user interface pro...On GitHub#59346
  10. Codex Extension failed in Visual Studio CodeOn GitHub#59151
Show all 53Show only the newest 10
  1. [Windows 10][VS Code] Codex 26.1021.22027 sidebar renderer_ready_timeout despite successful app-server initOn GitHub#58928
  2. Codex Fails to Start When Opening the Codex on WindowsOn GitHub#58866
  3. VS 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
  4. Why are you neglecting VS Code users?On GitHub Discussions#58810
  5. Bug of Extension in VS CodeOn GitHub#58803
  6. Codex VS Code extension webview fails on Windows 11 — rollback resolves issueOn GitHub#58582
  7. [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
  8. [Windows][VS Code] Codex 26.1021.22027 UI fails with renderer_ready_timeout; same UI error on a second computerOn GitHub#58354
  9. [Windows][VS Code] UI startup failure on 26.1021.22027; account requests and feedback fail on 26.1007.21434On GitHub#58150
  10. [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
  11. VS Code remote regression: 26.1021.22027 fails with renderer_ready_timeout; older version worksOn GitHub#58070
  12. Codex VS Code 26.1021.22027: startup preloads 3,045 JS modules and panel hits renderer_ready_timeout in a Linux devcontainerOn GitHub#58067
  13. VS Code WSL2: Codex Webview renderer_ready_timeout on startup, works after Stop Extension BisectOn GitHub#58049
  14. VS Code extension 26.1021.22027 fails to start UI in WSL Ubuntu; previous version worksOn GitHub#57812
  15. [VS Code / Dev Containers] 26.1021.22027 UI startup times out after ~3,000 asset requests; reload succeedsOn GitHub#57810
  16. [Windows] "Codex could not start – The extension could not start its user interface" (v26.51021.22027)On GitHub#57762
  17. [Linux/Wayland] Codex 26.1021.22027 fails to start UI and freezes VS Code 1.143.1 — downgrade fixes itOn GitHub#57759
  18. Recurring Codex VS Code extension startup failure on WindowsOn GitHub#57731
  19. Codex could not start The extension could not start its user interface.On GitHub#57600
  20. Error in VS while connecting codexOn the forum#1410267
  21. IDE extension webview fails at hard-coded 30-second startup timeout; timeout is not configurable and webview payload is 657 MiBOn GitHub#57531
  22. Title: Codex sidebar fails with renderer_ready_timeout on VS Code 1.143.1 (Windows 11), clean profileOn GitHub#57528
  23. [Windows / VS Code] 26.1021.22027 sidebar renderer_ready_timeout; rollback to 26.930.41038 restores startupOn GitHub#57421
  24. VS Code extension 26.1021.22027 fails to load UI on Windows — renderer_ready_timeoutOn GitHub#57368
  25. Title: [BUG][Windows][VS Code] Codex v26.1021.22027 fails to start UI — v26.1007.21434 worksOn GitHub#57344
  26. IDE Extension] Intermittent Codex sidebar renderer_ready_timeout on macOS and Remote-SSHOn GitHub#57306
  27. Title: [Windows] Codex VS Code extension fails to start — renderer_ready_timeoutOn GitHub#57064
  28. Codex IDE on Remote-SSH: recurring startup failure and gray-screen OOM — measured causes, failed fixes and maintainer questionsOn the forum#1409742
  29. [VS Code/Linux] Codex could not start its user interface in extension 26.1021.22027On GitHub#57032
  30. [IDE/Remote-SSH] 30s renderer_ready_timeout: quadratic preload scan + 3,203 eager assets; measured failures after mitigationOn GitHub#57026
  31. Bug Report — Codex VS Code Extension Fails to Start User Interface on LinuxOn GitHub#56992
  32. [VS Code Extension] Codex UI fails to start — renderer_ready_timeout after 30 seconds (Windows)On GitHub#56858
  33. Windows 10 (local VS Code): Codex IDE extension 26.1021.22027 fails with renderer_ready_timeout; 26.1007.21434 worksOn GitHub#56780
  34. VS Code Remote SSH: Codex webview never becomes ready (renderer_ready_timeout)On GitHub#56771
  35. Remote-SSH: Codex webview times out in 26.1021.22027; downgrading to 26.1007.21434 restores UIOn GitHub#56736
  36. VS Code extension 26.1021.22027: Codex UI fails to start with renderer_ready_timeoutOn GitHub#56710
  37. Linux desktop launch: Codex webview exhausts renderer RLIMIT_NOFILE=1024 (26.1021.22027)On GitHub#56703
  38. Codex 26.1021.22027 fails to start UI in VS Code 1.143.1 on WindowsOn GitHub#56691
  39. Codex VS Code Extension Fails to Initialize UI Even in an Isolated ProfileOn GitHub#56682
  40. [macOS Intel][VS Code] 26.1021.22027 fails with renderer_ready_timeout; 26.1007.21434 worksOn GitHub#56660
  41. UI doesn't start in VS Code extension 26.51021.22027On GitHub#56655
  42. Codex Extension (Webview) Fails After VS Code Update on WSL — WorkaroundOn the forum#1406245
  43. Codex WebView assets return HTTP 401 in VS Code Remote WSL after VS Code 1.141.1 updateOn GitHub#53840

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