vscode.dev: Extensions fail to load on Firefox 136

[SoCuul]

Type: Bug

When visiting the extensions panel, it says "Error while fetching extensions. NetworkError while attempting to fetch resource."

Looking into the developer console, it gives the following log statements

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://marketplace.visualstudio.com/_apis/public/gallery/extensionquery. (Reason: CORS request did not succeed). Status code: (null).

INFO Ignoring following additional builtin extensions as there is an error while fetching them from gallery 
 Array []
 NetworkError when attempting to fetch resource. workbench.web.main.internal.js:34:2613

This is reproducible on both vscode.dev stable and insiders.

VS Code version: Code - Insiders 1.98.0-insider (6609ac3d66f4eade5cf376d1cb76f13985724bcb, 2025-03-04T19:22:25.096Z) OS version: macOS Sequoia 15.3.1

System Info: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:136.0) Gecko/20100101 Firefox/136.0Extensions: none

[bpasero]

I cannot reproduce, so I suspect a configuration issue in your installation.

[SoCuul]

I tried to create a new firefox profile, and in the new profile the issue does not arise. What in my profile could be causing this to happen? I tried disabling all extensions installed and it still did not resolve this issue.

[bpasero]

I suggest then to report an issue to FF.

[benblank]

This appears to be a result of Firefox's "Enhanced Tracking Protection". Adding an exception for vscode.dev allowed extensions to load normally for me and the following message appeared when selecting the previously-blocked entry in the Web Developer Tools > Network tab:

I'm not sure why the request is getting blocked, but the relevant documentation suggests that the domain marketplace.visualstudio.com has been "identified as engaging in cross-site tracking of users":

Content is blocked based on the domain from which it is to be loaded.

Firefox ships with a list of sites which have been identified as engaging in cross-site tracking of users. When tracking protection is enabled, Firefox blocks content from sites in the list.

Sites that track users are most commonly third-party advertising and analytics sites.

TL;DR — In Firefox > Settings > Privacy & Security > Enhanced Tracking Protection, click on "Manage exceptions…" and add vscode.dev.

[SoCuul]

Oh, that's completely solved the problem. Thank you!