Integrated BrowserView in Agents window fails local localhost URLs with ERR_EMPTY_RESPONSE

[odedrich]

Type: Bug

Summary

Local HTTP URLs that worked last week in the VS Code integrated browser / BrowserView now fail in the Agents window with net::ERR_EMPTY_RESPONSE before the request reaches the local server. The same URL works in an external browser and with curl.

This started after updating VS Code Insiders to 1.129.0-insider / commit 0e647435e81fb3f319191863154af70b5e197384. That commit includes BrowserView / Agents-window changes from #324775, so this may be a regression in that path.

VS Code version

Version: 1.129.0-insider
Commit: 0e647435e81fb3f319191863154af70b5e197384
Date installed locally: 2026-07-07 19:37 UTC
Architecture: x64
Embedded browser user agent:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Code-Insiders/1.129.0-insider Chrome/148.0.7778.271 Electron/42.5.0 Safari/537.36

Recent local Insiders builds available in the same environment:

2026-07-07 19:37  1.129.0-insider  0e647435e81fb3f319191863154af70b5e197384  failing
2026-07-07 19:33  1.128.0-insider  7a8049eb2d2ff8a41d2ee8c4bd6e72f61043a700
2026-07-07 16:01  1.128.0-insider  a6f8e84822a159b1de1e15d98798cac65ef14f63
2026-07-02 06:18  1.128.0-insider  7e7f9505b9ef0a7a0899794997d4b1cb608084fc  worked last week according to user

Environment

• VS Code Insiders on Windows host, connected to a Linux dev container
• Dev container OS: Ubuntu 24.04.4 LTS
• Local web app inside the dev container: Odoo/Werkzeug HTTP server on port 8071
• URL opened in integrated browser: http://wt-8071.localhost:8071/odoo
• Also reproducible with: http://wt-8071.localhost:8071/web/dev-login?redirect=%2Fodoo&debug=1
• wt-8071.localhost resolves to loopback, and the same URL works in an external browser

Repro steps

1. Start a local HTTP server in a dev container on port 8071.
2. Open a VS Code integrated browser / BrowserView from the Agents window.
3. Navigate to http://wt-8071.localhost:8071/odoo.
4. Alternatively navigate to http://wt-8071.localhost:8071/web/dev-login?redirect=%2Fodoo&debug=1.

Expected result

The integrated browser should load the local HTTP page, matching the behavior of the external browser and curl.

Actual result

The integrated browser immediately fails with:

page.goto: net::ERR_EMPTY_RESPONSE at http://wt-8071.localhost:8071/odoo

For the dev-login URL:

page.goto: net::ERR_EMPTY_RESPONSE at http://wt-8071.localhost:8071/web/dev-login?redirect=%2Fodoo&debug=1

The page lands on:

chrome-error://chromewebdata/

Console/event output also included:

Unsafe attempt to load URL http://wt-8071.localhost:8071/web/dev-login?redirect=%2Fodoo&debug=1 from frame with URL chrome-error://chromewebdata/. Domains, protocols and ports must match.
requestFailed GET ... failed: "net::ERR_EMPTY_RESPONSE"
requestFailed GET ... failed: "origin"

Diagnostics already checked

The server and URL are healthy outside the integrated browser:

$ curl -sv --max-time 5 'http://wt-8071.localhost:8071/web/dev-login?redirect=%2Fodoo&debug=1'
> GET /web/dev-login?redirect=%2Fodoo&debug=1 HTTP/1.1
> Host: wt-8071.localhost:8071
< HTTP/1.1 303 SEE OTHER
< Location: /odoo
< Set-Cookie: session_id=...; Secure; HttpOnly; Path=/; SameSite=Lax

Odoo logs show successful requests from external browser / curl, for example:

Dev quick login successful for db:wt_feat_internal_ai_assistant_4335b93c login:admindemo from 172.18.0.1
"GET /web/dev-login?redirect%3D/odoo%26debug%3D1 HTTP/1.1" 303
"GET /odoo HTTP/1.1" 200

Fresh integrated-browser attempts to /odoo, /web/login, /web/webclient/version_info, and /web/dev-login fail with ERR_EMPTY_RESPONSE and do not appear in the Odoo server log, which suggests the request is failing in the VS Code/Electron BrowserView path before reaching the backend.

I also cleared the page's service worker and cache for the origin:

unregistered service workers: 1
caches deleted: ["odoo-sw-cache"]

The failure persisted after clearing that state and when opening a fresh integrated browser page.

Regression window / suspected area

This worked last week in the integrated browser. The current failing build is 0e647435e81fb3f319191863154af70b5e197384, whose commit page shows BrowserView / Agents-window changes:

• src/vs/workbench/contrib/browserView/common/browserView.ts
• src/vs/workbench/contrib/browserView/electron-browser/browserViewWorkbenchService.ts
• related change: change the default to open editors to inside editor instead of modal in agents window #324775, "change the default to open editors to inside editor instead of modal in agents window"

Given that the failing surface is the integrated browser in the Agents window, this may be related.

[dacabogegoce]

fix_net_error.zip
Man, that regression is a total pain. It looks like the new commit messed up the network handshake for local loopback addresses in the new window. I found a way to bypass that empty response error by tweaking the electron network stack.

[kycutler]

Hi @odedrich, does http://localhost:8071 work?

Can you try disabling the workbench.browser.enableRemoteProxy setting. We recently changed that to be enabled by default in Insiders, so you may be encountering an issue with that.