Theia IDE 1.70.x Preview Testing

[jfaltermeier]

The new version 1.70.0 of the Theia IDE is available on the preview channel now. Please join the preview testing!

You can download it here:

• Linux
• Mac x86
• Mac ARM
• Windows

Update your existing installation by setting the preference updates.channel to preview.

Please respond here when you can test the preview without finding blockers, by commenting with a ✔️.
If you find any issues, please mention them in this thread and report them as an issue once confirmed by other testers.

Phase	Target	Status
1.70.0 preview available	2026-03-27	✅
1.70.0 community preview window	2026-03-27 → 2026-04-08	⛔ blockers found
1.70.100 preview available	2026-04-08	✅
1.70.100 community preview window	2026-04-08 → 2026-04-10	⛔ blocker found
1.70.200 preview available	2026-04-10	✅
1.70.200 community preview window	2026-04-10 → 2026-04-13	⏳
Theia IDE 1.70.x Promoted to Stable	2026-04-14
Docker image Publish	2026-04-14
Snap updated	2026-04-14

[tfroment]

Hi,
I have identified a non critical regression in the Coder agent: #17264
Otherwise, everything looks good, although I am only performing basic tests and not running comprehensive regression testing 🙂

[ndoschek]

Hi Thomas, thanks a lot for raising this!
We also discussed this internally, this approach has still some issues.
We'll take care of smoothing this out.

[ndoschek]

We've decided to prepare a patch release to mainly address the mentioned disruptive agent mode confirmation UX

Please follow the endgame checklist here:

• 1.70.1 endgame plan #17267

We expect an updated preview towards the start of the next week.

[ngfelixl]

Hi everyone :)

I've noticed a problem, probably with Electron. When I run the TheiaIDE app 1.70.0 from the download link above, it sometimes does not start properly. The splash image appears, the main window appears (empty), then everything disappears. This did not happen in 1.69.0 at all. In TheiaIDE this also not too frequently (maybe around 10-20% of the starts), however in my Theia derivate it happens in 50% of the starts.

In addition to that, the app close appears to be very slow now, too. Starting with a "disconnected" and then closes after a few seconds. 1.69.0 closed much quicker. Both points are visible in the attached video.
Edit: The long close only happens, when closing via "x" in top right. When closing via Taskbar > Close window, it's all good.

I noticed it on Windows only, Linux seems to be fine.
Thanks for all your efforts!

theia-ide-electron-issue.mp4

[ndoschek]

Hi @ngfelixl, we've published a new preview 1.70.100 which includes the fix for the slow close on Windows (#17296), thanks again for helping test that PR! 🎉

Could you give 1.70.100 a try and let us know whether the intermittent startup crash still occurs? I've been testing with the new version in my Windows VM as well but unfortunately still can't reproduce it on my end. Your feedback would be really helpful! TIA!

[ndoschek]

Also, I just tested this approach to get more logging, could you also try capturing the startup logs on a failed start? You can do this by modifying your desktop shortcut: right-click it > Properties, and change the Target to like this (with your paths):

cmd /c ""C:\Users\user\AppData\Local\Programs\TheiaIDE\TheiaIDE.exe" --log-level=trace > "C:\Users\user\theia-startup.log" 2>&1"

Could you check if it contains any suspicisous output that stops mid-startup, that could help us narrow down where it fails. TIA

[ngfelixl]

Hi @ndoschek, you are welcome. The crash still occurs with 1.70.1. It's happening more likely, when clicking/dragging inside the splash screen image. Suspicious parts of the trace log during a failed start are:

[...]

2026-04-09T10:27:04.199Z root ERROR Uncaught Exception:  Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
2026-04-09T10:27:04.199Z root ERROR Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
    at ServerResponse.setHeader (node:_http_outgoing:700:11)
    at E.set.E.header (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\637.js:2:56421)
    at E.send (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\637.js:2:52063)
    at E.json (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\637.js:2:53171)
    at i.isInitialized (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\main.js:1:9869)
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
2026-04-09T10:27:04.199Z root ERROR Desktop files can only be created if there is a set HOME directory
2026-04-09T10:27:04.199Z root ERROR Uncaught Exception:  Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
2026-04-09T10:27:04.199Z root ERROR Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
    at ServerResponse.setHeader (node:_http_outgoing:700:11)
    at E.set.E.header (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\637.js:2:56421)
    at E.send (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\637.js:2:52063)
    at E.json (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\637.js:2:53171)
    at i.isInitialized (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\main.js:1:4833)
    at C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\main.js:1:4591
    at o.handle_request (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\637.js:2:64225)
    at s (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\637.js:2:65658)
    at p.dispatch (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\637.js:2:65684)
    at o.handle_request (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\637.js:2:64225)
2026-04-09T10:27:04.200Z root DEBUG Frontend u.onStart: 0.9 ms [Finished 2.188 s after frontend start]

[...]

2026-04-09T10:27:06.183Z root WARN Linked preference "debug.node.autoAttach" not found.
2026-04-09T10:27:06.251Z root INFO Frontend application start: 2306.5 ms [Finished 5.291 s after backend start]
(node:102096) UnhandledPromiseRejectionWarning: Error: Cancelled
    at d (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\69.js:2:24825)
    at C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\69.js:2:135696
    at C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\69.js:2:51002
    at s.invoke (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\69.js:2:51091)
    at a.fire (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\69.js:2:52961)
    at c.cancel (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\69.js:2:24060)
    at t.CancellationTokenSource.cancel (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\69.js:2:24615)
    at l (C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\767.js:1:20219)
    at C:\Users\User1\AppData\Local\Programs\TheiaIDE\resources\app.asar\lib\backend\767.js:1:20357
(Use `TheiaIDE --trace-warnings ...` to show where the warning was created)
2026-04-09T10:27:06.262Z root INFO Copilot: discovered 3 available models: gpt-4o-mini, gpt-4o, gpt-3.5-turbo
(node:102096) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)
2026-04-09T10:27:06.263Z root INFO Replace loading indicator with ready workbench UI (animation): 1868.5 ms [Finished 4.276 s after frontend start]
2026-04-09T10:27:06.263Z root INFO Changed application state from 'initialized_layout' to 'ready'.
END_OF_LOG

[ndoschek]

Hi again, thanks so much for the hint about clicking/dragging the splash screen, that was the right pointer! I noticed that even just hovering over the splash screen is enough to reproduce it reliably on my end.

I could track this down to a known Electron bug (electron/electron#50040): a use-after-free in the native non-client hit-test handling during frameless window teardown, introduced in Electron v39.6.1. Since we upgraded from Electron 38.4.0 to 39.7.0 for 1.70.0, we landed right in the affected range. The fix was backported to Electron v39.8.1 (electron/electron#50042).

I'm currently testing with the patched Electron version and will follow up once confirmed!

[ndoschek]

Good news, this seems to work, I tested with the electron theia application and can already observe that this works even when interacting with the splash screen in my VM 👍
I created an issue and opened the PRs and also plan another patch for that

[Roger-Gu]

Hi everyone. As discussed in #17215 and #17223, there have been issues with function and instruction breakpoints in v1.69. Both problems seem to be solved, Thanks for the effort!
However, a new problem is introduced: #17276
When adding or removing a function/instruction breakpoint, it would not be reflected in the breakpoints view immediately. Instead, one have to remove or add a source breakpoint to trigger the update.
It will still stop at a new (although unseen) breakpoint, and the list of breakpoints would be correct when the view is refreshed after adding/removing source breakpoint, so I think the problem might be that adding/removing function and instruction breakpoints is not properly triggering the UI update of the breakpoint view.

[ndoschek]

Hi @Roger-Gu, glad to hear the breakpoint issues from 1.69 are resolved! Thanks for filing #17276 for the view refresh problem, we'll look into it 👀

[jfaltermeier]

The new version 1.70.100 of the Theia IDE is available on the preview channel now. Please join the preview testing!

You can download it here:

• Linux
• Mac x86
• Mac ARM
• Windows

Update your existing installation by setting the preference updates.channel to preview.

Please respond here when you can test the preview without finding blockers, by commenting with a ✔️.
If you find any issues, please mention them in this thread and report them as an issue once confirmed by other testers.

[Roger-Gu]

Seems to work well! #17215, #17223, and #17276 are all fixed! Thanks for the effort! ✔️

[tfroment]

Everything looks good on my side (and #17264 is fixed as well), thanks a lot!

[jfaltermeier]

The new version 1.70.200 of the Theia IDE is available on the preview channel now. Please join the preview testing!

You can download it here:

• Linux
• Mac x86
• Mac ARM
• Windows

Update your existing installation by setting the preference updates.channel to preview.

Please respond here when you can test the preview without finding blockers, by commenting with a ✔️.
If you find any issues, please mention them in this thread and report them as an issue once confirmed by other testers.