2018619 - Restricted error text does not appear when accessing restricted pages (internal/non-internal)

Status: NEW

(Firefox Enterprise :: Client, defect, P1)

Description

[Peter Magyari (Desktop QA)]

Attachment: No-error-page.png

Found in

• Firefox Enterprise 149.0a1 (2026-02-21)

Tested platforms

• Affected platforms: Windows 11/ MacOS 15 / Ubuntu 24.04

Steps to reproduce

1. Open Firefox Enterprise.
2. Log-in to https://stage.fx-enterprise.nonprod.webservices.mozgcp.net using valid credentials.
3. Set the BlockAboutSupport policy (or any other page blocking policy) to true.
4. Navigate to the blocked page (about:support in this case).

Expected result

• The user is presented with an error page which states "This website has been blocked by your Organization...etc"

Actual result

• Page is blocked but blank.

Notes

• This also occurs on non-internal pages. (using WebsiteFilter to block a page then trying to access it won't show error message)

Comment 1

[Brian Thomas Smith [:bsmth]]

Attachment: ChromeUtils not defined

Checking the console here, I see:

Uncaught ReferenceError: ChromeUtils is not defined
    <anonymous> chrome://global/content/errors/net-errors.mjs:11

Comment 2

[:gerard-majax]

This was regressed by https://searchfox.org/enterprise-main/diff/786769607b00a9a1d2160cfd7d19e1091797941f/toolkit/content/errors/net-errors.mjs#11 and is related to https://bugzilla.mozilla.org/show_bug.cgi?id=2009206, looks like ChromeUtils does not work there.