2027209 - Increase error code visibility on net error pages

Status: RESOLVED FIXED

(Firefox :: Security, defect, P2)

Description

[Jack Brown]

A Reddit thread surfaced user complaints that the new Felt Privacy error pages don't show error codes. Investigation suggests this might not be a straightforward regression, since the specific errors shown in the screenshot (connectionFailure/netInterrupt) never showed error codes in the old UI either.

The real issue could be broader, since this affects all net errors that go through the customNetError template in net-error-card.mjs. These error configs are all defined in net-errors.mjs, but not every config in that file is affected.

A decision is needed on which of these net errors should actually display their error code. If any should, the fix is straightforward: update customNetErrorSectionTemplate in net-error-card.mjs to render the error code when present in the config, and ensure the relevant registry entries have the correct errorCode values.

Comment 1

[Mathew Hodson]

This looks like a duplicate of bug 2023800

Comment 2

[Jack Brown]

Error ID	Displayed Code	Reason NOT to show	Reason to show	Show?
NS_ERROR_OFFLINE	NS_ERROR_OFFLINE		Real NS_ERROR_* code. meaningful for support and diagnostics	TBD
blockedByCOOP	NS_ERROR_DOM_COOP_FAILED		Real NS_ERROR_* code. directly actionable for web devs debugging COOP headers	TBD
blockedByCOEP	NS_ERROR_DOM_COEP_FAILED		Real NS_ERROR_* code. directly actionable for web devs debugging COEP headers	TBD
netReset			Useful to distinguish from other connection errors in bug reports	TBD
connectionFailure			Common. helps users search for solutions and file useful bug reports	TBD
netInterrupt			Distinguishes mid-transfer failures from initial connection failures	TBD
netTimeout			Distinguishes timeout from refused/reset	TBD
dnsNotFound			Very common. well-recognised by users and support staff	TBD
httpErrorPage			COMPLETE: Bug 2023800 already surfaces the HTTP status code and text in the intro via responsestatus/responsestatustext.	Yes
serverError			COMPLETE: Bug 2023800 already surfaces the HTTP status code and text in the intro.	Yes
invalidHeaderValue			Useful for web devs diagnosing malformed response headers	TBD
deniedPortAccess		Firefox security policy. not actionable by the user or support. Bug 2024150 (currently reverted) also removed whatCanYouDoL10nId from this config, treating it as having no remediation steps at all		TBD
malformedURI		User typed an invalid URL. "malformedURI" is semantically identical to the page title and doesn't help them fix it		TBD
captivePortal		Single clear action (open login portal). code has no actionable or diagnostic value		TBD
contentEncodingError			Identifies server-side encoding misconfigurations. useful for reporting to site owners	TBD
corruptedContentErrorv2			Distinguishes corruption from other transfer errors	TBD
fileAccessDenied		Local file permission error. code restates the title with no additional diagnostic value		TBD
fileNotFound			COMPLETE: Bug 2018850 added file-specific messaging (actual file path, file-oriented advice).	Yes
inadequateSecurityError			Identifies weak TLS configuration specifically. useful for tech support	TBD
netOffline			Distinguishes browser offline mode from actual connectivity failures	TBD
networkProtocolError			Identifies HTTP/2 or HTTP/3 protocol-level failures	TBD
notCached		Informational only. code doesn't help the user or support take any action		TBD
nssFailure2			Helps support identify NSS library failures	TBD
proxyConnectFailure			Useful for proxy configuration diagnosis	TBD
vpnFailure			Useful for IT support troubleshooting VPN connectivity	TBD
proxyResolveFailure			Distinguishes proxy DNS failures from proxy connection failures	TBD
redirectLoop			Helps users report the specific condition to site owners	TBD
sslv3Used			Identifies the specific obsolete protocol. useful for tech support	TBD
unknownProtocolFound			Identifies unrecognised URI scheme issues	TBD
unknownSocketType			Useful for tech support diagnosing misconfigured socket types	TBD
unsafeContentType			Identifies a MIME-type safety issue. useful for web devs	TBD
cspBlocked			Useful for web devs debugging CSP configurations	TBD
xfoBlocked			Useful for web devs debugging X-Frame-Options configurations	TBD

Comment 3

[Jared Wein [:jaws] (please needinfo? me)]

I've updated the table below with what we should do in bold. Some of the pages I marked no because the text on the page is specific enough to already describe the error.

(In reply to Jack Brown from comment #2)

Error ID	Displayed Code	Reason NOT to show	Reason to show	Show?
NS_ERROR_OFFLINE	NS_ERROR_OFFLINE		Real NS_ERROR_* code. meaningful for support and diagnostics	Yes
blockedByCOOP	NS_ERROR_DOM_COOP_FAILED		Real NS_ERROR_* code. directly actionable for web devs debugging COOP headers	Yes
blockedByCOEP	NS_ERROR_DOM_COEP_FAILED		Real NS_ERROR_* code. directly actionable for web devs debugging COEP headers	Yes
netReset			Useful to distinguish from other connection errors in bug reports	Yes
connectionFailure			Common. helps users search for solutions and file useful bug reports	Yes
netInterrupt			Distinguishes mid-transfer failures from initial connection failures	Yes
netTimeout			Distinguishes timeout from refused/reset	Yes
dnsNotFound			Very common. well-recognised by users and support staff	Yes
httpErrorPage			COMPLETE: Bug 2023800 already surfaces the HTTP status code and text in the intro via responsestatus/responsestatustext.	Yes
serverError			COMPLETE: Bug 2023800 already surfaces the HTTP status code and text in the intro.	Yes
invalidHeaderValue			Useful for web devs diagnosing malformed response headers	Yes
deniedPortAccess		Firefox security policy. not actionable by the user or support. Bug 2024150 (currently reverted) also removed whatCanYouDoL10nId from this config, treating it as having no remediation steps at all		No
malformedURI		User typed an invalid URL. "malformedURI" is semantically identical to the page title and doesn't help them fix it		No
captivePortal		Single clear action (open login portal). code has no actionable or diagnostic value		No
contentEncodingError			Identifies server-side encoding misconfigurations. useful for reporting to site owners	Yes
corruptedContentErrorv2			Distinguishes corruption from other transfer errors	TBD
fileAccessDenied		Local file permission error. code restates the title with no additional diagnostic value		No
fileNotFound			COMPLETE: Bug 2018850 added file-specific messaging (actual file path, file-oriented advice).	Yes
inadequateSecurityError			Identifies weak TLS configuration specifically. useful for tech support	No
netOffline			Distinguishes browser offline mode from actual connectivity failures	Yes
networkProtocolError			Identifies HTTP/2 or HTTP/3 protocol-level failures	No
notCached		Informational only. code doesn't help the user or support take any action		No
nssFailure2			Helps support identify NSS library failures	No
proxyConnectFailure			Useful for proxy configuration diagnosis	No, because error page already has proxy-specific language
vpnFailure			Useful for IT support troubleshooting VPN connectivity	No, because error page already has VPN-specific language
proxyResolveFailure			Distinguishes proxy DNS failures from proxy connection failures	No
redirectLoop			Helps users report the specific condition to site owners	No
sslv3Used			Identifies the specific obsolete protocol. useful for tech support	No
unknownProtocolFound			Identifies unrecognised URI scheme issues	No
unknownSocketType			Useful for tech support diagnosing misconfigured socket types	No
unsafeContentType			Identifies a MIME-type safety issue. useful for web devs	No
cspBlocked			Useful for web devs debugging CSP configurations	No
xfoBlocked			Useful for web devs debugging X-Frame-Options configurations	No

Comment 4

[Jack Brown]

Attachment: Bug 2027209 - Show error code on customNetError pages - r=niklas

Comment 5

[Jack Brown]

Catalog of errors to update, how to reproduce them, and screenshots of each page before/after:
https://docs.google.com/document/d/1J3i8-qtXiYlXDuIXf-RoUMBr6fPXChG6rWxJGWgcuCo/edit?usp=sharing

Run an old version of Firefox, such as mach mozregression --launch 2025-11-01, to check old pages.

Comment 6

[Jack Brown]

Attachment: Bug 2027209 - Update netInterrupt Felt Privacy error page content - r=niklas

Comment 7

[Jack Brown]

Attachment: Bug 2027209 - Update connectionFailure and netTimeout Felt Privacy error page content - r=niklas,jaws

Comment 8

[Jack Brown]

Attachment: Bug 2027209 - Update invalidHeaderValue and contentEncodingError Felt Privacy error page content - r=niklas,jaws

Comment 9

[Manuel Bucher [:manuel] {{ FYI: OOO Jul 30 - Aug 16 }}]

Attachment: content-encoding.png

I was just about to open a bug about contentEncodingError, but saw that it is getting at least partly addressed in this bug, so adding information here:

Like HTTP error that were updated in Bug 2023800, the error contentEncodingError happens after establishing the connection to the server. It is also somewhat later due to being an error about the HTTP body, not HTTP headers. We should both:

1. Show the HTTP status code if it is an error (similar to Bug 2023800) and
2. Replace the phrase "can’t connect to the server at" with something that describes the situation more correctly.

I'm attach a screenshot of how it looks like now/before. Sorry, I'm unable to share the website, because it is a private one. And I haven't found a good test website / haven't setup one yet.

I see that (2) is currently getting addressed here. However, I was wondering whether (1) could get addressed here too, or whether I should open a separate bug for that. This might be true for other errors too.

Comment 10

[Jared Wein [:jaws] (please needinfo? me)]

@manuel, can you please open a new bug for the status code? Since that might affect other errors, I don't want to slow down the momentum here while we research each code to update. I want to get the changes in this bug in for 151 and the window for string changes closes today.

Comment 11

[Jack Brown]

Attachment: Bug 2027209 - Update invalidHeaderValue and contentEncodingError Felt Privacy error page content - r=niklas,jaws

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/8a540e7c99aa
https://hg.mozilla.org/integration/autoland/rev/267da15baa9d
Update invalidHeaderValue and contentEncodingError Felt Privacy error page content - r=fluent-reviewers,bolsson,mkaply

Comment 13

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/267da15baa9d

Comment 14

[Jared Wein [:jaws] (please needinfo? me)]

Reopening as we have two more patches we want to land for this work. We just landed the strings in advance.

Comment 15

[Jack Brown]

Attachment: Bug 2027209 - Update connectionFailure and netTimeout Felt Privacy error page content - r=niklas,jaws

Comment 16

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/677aa4508467
https://hg.mozilla.org/integration/autoland/rev/2a662ab79785
Show error code on customNetError pages - r=rking

Comment 17

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/614d04d43008
https://hg.mozilla.org/integration/autoland/rev/c90127341954
Update netInterrupt Felt Privacy error page content - r=rking,desktop-theme-reviewers,sfoster

Comment 18

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/2a662ab79785
https://hg.mozilla.org/mozilla-central/rev/c90127341954

Comment 19

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/1c1b301235b6
https://hg.mozilla.org/integration/autoland/rev/5a3498e16523
Update connectionFailure and netTimeout Felt Privacy error page content - r=rking

Comment 20

[Jack Brown]

Attachment: Bug 2027209 - Show error code on customNetError pages -

Affected errors:

NS_ERROR_OFFLINE
NS_ERROR_DOM_COOP_FAILED (blockedByCOOP)
NS_ERROR_DOM_COEP_FAILED (blockedByCOEP)
NS_ERROR_NET_EMPTY_RESPONSE (netReset)

Original Revision: https://phabricator.services.mozilla.com/D294024

Comment 21

[Jack Brown]

Attachment: Bug 2027209 - Update netInterrupt Felt Privacy error page content -

Original Revision: https://phabricator.services.mozilla.com/D294693

Comment 22

[Phabricator Automation]

firefox-beta Uplift Approval Request

• User impact if declined/Reason for urgency: The Felt Privacy error page redesign shipped with terse or missing error messages/codes for several common network failures (connectionFailure, netTimeout, netInterrupt). Users and support staff rely on these codes to diagnose issues. Declining means Firefox 151 users see less informative error pages.
• Code covered by automated testing?: yes
• Fix verified in Nightly?: yes
• Needs manual QE testing?: no
• Steps to reproduce for manual QE testing:
• Risk associated with taking this patch: low
• Explanation of risk level: Changes are confined to the error page rendering path. Normal browsing is completely unaffected. Automated tests cover each affected error type.
• String changes made/needed?: N/A
• Is Android affected?: no

Comment 23

[Jack Brown]

Attachment: Bug 2027209 - Update connectionFailure and netTimeout Felt Privacy error page content -

Original Revision: https://phabricator.services.mozilla.com/D295527

Comment 24

[Serban Stanca [:SerbanS]]

https://hg.mozilla.org/mozilla-central/rev/5a3498e16523

Comment 25

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/ae66294cbe34
https://hg.mozilla.org/releases/mozilla-beta/rev/289237d77768
https://github.com/mozilla-firefox/firefox/commit/6d23858c08d5
https://hg.mozilla.org/releases/mozilla-beta/rev/8004bb58d93d
https://github.com/mozilla-firefox/firefox/commit/6b0acfb76165
https://hg.mozilla.org/releases/mozilla-beta/rev/608a480a3921