Theia IDE 1.66.x Preview Testing

[jfaltermeier]

The new version 1.66.0 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
1.66.0 preview available	2025-11-03	✅
1.66.0 community preview window	2025-11-03 → 2025-11-09	⛔ blockers found
1.66.100 preview available	2025-11-10	✅
1.66.100 community preview window	2025-11-10 → 2025-11-11	⛔ blockers found
1.66.200 preview available	2025-11-11	✅
1.66.200 community preview window	2025-11-11 → 2025-11-12	✅
Theia IDE 1.66.x Promoted to Stable	2025-11-12 (EOD)	✅
Docker image Publish	2025-11-12 (EOD)	✅
Snap updated	2025-11-12 (EOD)	✅

[ndoschek]

There is an issue with changed behavior of the explorer tree selections: #16528
We are already working on a fix, and it will likely be a candidate for a patch.

[CamilleLetavernier]

This could be a similar issue, but for broken auto-scroll behavior in the AI Chat View: #16536

[ndoschek]

I am not sure, but perhaps, I think the chat view is also a tree-widget? There is already a fix by Eugen that removes the smooth animation forceful centering again.
However the scroll lock works fine for me with 1.66.0, both temporary and via the lock button.

[ndoschek]

Both #16528 and #16536 have been addressed and the fixes will be included in the upcoming next preview version (ETA later today).

[tsmaeder]

I getting this error when opening a java-based workspace on Windows:

Activating plugin 'Extension Pack for Java' failed: Cannot find module 'C:\Users\thomas\AppData\Local\Programs\TheiaIDE\resources\app\plugins\vscjava.vscode-java-pack\extension\out\extension' 
Require stack: 
- C:\Users\thomas\AppData\Local\Programs\TheiaIDE\resources\app\lib\backend\339.js 
- C:\Users\thomas\AppData\Local\Programs\TheiaIDE\resources\app\lib\backend\plugin-host.js

[tsmaeder]

When I look at the package directory, there is no code there, only the package.json and resources. Note that while it's called an "extension pack", it's an extension in it's own right, containing code.
@ndoschek did we recently publish new versions of the built-ins?

[tsmaeder]

I also have version 0.29 in my install folder, but with the code missing. The updated versions of plugins are not surprising: extension packs don't reference a particular version, so we end up with "newest compatible version".

[ndoschek]

As for Ubuntu I cannot see any install folder for the extensions, maybe there's a different mechanism on Windows for the installation process or I'm overlooking something.
@jfaltermeier @sgraband do you have an idea what could be the problem there?

[tsmaeder]

FWIW, I reinstalled Theia from scratch and deleted all installed extensions and the problem persists

[ndoschek]

So I found something in the logs that could explain this, for the windows installer (Windows: Create Installer stage log) the plugin download logged:

$ theia download:plugins --rate-limit=15 --parallel=false && yarn permissions:writeable
--- downloading plugins ---
- eclipse-theia.builtin-extension-pack: already downloaded - skipping
- vscjava.vscode-java-pack: already downloaded - skipping
+ vscjava.vscode-java-dependency: downloaded successfully 

while for the linux installer (Linux: Create Installer stage log) for example:

$ theia download:plugins --rate-limit=15 --parallel=false && yarn permissions:writeable
--- downloading plugins ---
+ eclipse-theia.builtin-extension-pack: downloaded successfully 
+ vscjava.vscode-java-pack: downloaded successfully 
+ vscjava.vscode-java-dependency: downloaded successfully 

We'll look into it, to hopefully fix this with the upcoming patch.

[ndoschek]

I tested in my Windows VM and can confirm that the extensions work again as expected if the plugins are properly downloaded, i.e. when the preview build starts from a clean state. I updated the Windows preview build to fix this oversight.
So this is expected to be resolved with the next preview version (ETA later today).

[ndoschek]

There is also an issue with accessing environment variables in the new IDE version (see eclipse-theia/theia-ide#601, originally reported by @eneufeld, thanks)

@jfaltermeier or @sgraband, do you have any idea what might be causing this?

[sgraband]

No sorry no idea where this may come from. Maybe the electron update?

[ndoschek]

We found that this is likely a configuration issue rather than a recent regression, so it shouldn't block the release.
We'll investigate further and probably it is enough to update the documentation accordingly.

[ndoschek]

The new version 1.66.100 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.

[jfaltermeier]

The new version 1.66.200 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.

[tsmaeder]

✔️

[sgraband]

✔️

[JonasHelming]

🏁

[jfaltermeier]

✔️

[MalcolmMielle]

I have a problem with the monaspace font: #16569

[jfaltermeier]

1.66.200 has been promoted to stable