2010739 - Disable Compression Dictionaries in 147+

Status: VERIFIED FIXED

(Core :: Networking: Cache, task)

Description

[Randell Jesup [:jesup] (needinfo me)]

ChatGPT is broken if compression dictionaries is enabled.

Comment 1

[Randell Jesup [:jesup] (needinfo me)]

Attachment: Bug 2010739: Disable Compression Dictionaries r=mt!

Comment 2

[Phabricator Automation]

firefox-beta Uplift Approval Request

• User impact if declined: ChatGPT breakage
• Code covered by automated testing: yes
• Fix verified in Nightly: yes
• Needs manual QE test: yes
• Steps to reproduce for manual QE testing: Check ChatGPT works with studies disabled
• Risk associated with taking this patch: low
• Explanation of risk level: pref flip, already in experiment
• String changes made/needed: none
• Is Android affected?: yes

Comment 3

[Randell Jesup [:jesup] (needinfo me)]

Attachment: Bug 2010739: Disable Compression Dictionaries

Original Revision: https://phabricator.services.mozilla.com/D279239

Comment 4

[Phabricator Automation]

firefox-release Uplift Approval Request

• User impact if declined: ChatGPT breakage
• Code covered by automated testing: yes
• Fix verified in Nightly: yes
• Needs manual QE test: yes
• Steps to reproduce for manual QE testing: Check ChatGPT works with studies disabled
• Risk associated with taking this patch: low
• Explanation of risk level: pref flip, already in experiment
• String changes made/needed: none
• Is Android affected?: yes

Comment 5

[Randell Jesup [:jesup] (needinfo me)]

Attachment: Bug 2010739: Disable Compression Dictionaries

Original Revision: https://phabricator.services.mozilla.com/D279239

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/7ac3827200d5
https://hg.mozilla.org/integration/autoland/rev/ff0c431f2956
Disable Compression Dictionaries r=mt

Comment 7

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/9a422459a7c3
https://hg.mozilla.org/releases/mozilla-beta/rev/b6dc99f66034

Comment 8

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/a7dd9359671c
https://hg.mozilla.org/releases/mozilla-release/rev/262513a2ad8a

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/b74fc4aba62e
https://hg.mozilla.org/integration/autoland/rev/0b8d77107c82
Revert "Bug 2010739: Disable Compression Dictionaries r=mt" for causing wpt failures in decoded-body-size-compressed.https.html.

Comment 10

[Serban Stanca [:SerbanS]]

Reverted this because it was causing wpt failures in decoded-body-size-compressed.https.html.

• Revert link
• Push with failures
• Failure Log
• Failure line: TEST-UNEXPECTED-FAIL | /resource-timing/decoded-body-size-compressed.https.html | decodedBodySize for dictionary-compressed brotli (dcb) resource - promise_test: Unhandled rejection with value: object "TypeError: Decoding failed."

Comment 11

[Daniel Holbert [:dholbert]]

I've got a patch that should address comment 10 in bug 2010762.

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/fe9f18325f7e
https://hg.mozilla.org/integration/autoland/rev/db30ed336471
Disable Compression Dictionaries r=mt

Comment 13

[Daniel Holbert [:dholbert]]

Important note for release managers: you'll need to land the uplift-patches in bug 2010762 on beta/release branches before landing the uplift-patches in this bug here.

(If it's convenient, feel free to wire them together as a patch stack; or uplift bug 2010762 first before uplifting this bug -- whatever works best for your workflow.)

That will prevent those branches from hitting the failure in comment 10.

Comment 14

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/c081f3f7d219
https://hg.mozilla.org/mozilla-central/rev/79c680d8be01
Disable Compression Dictionaries r=mt

Comment 15

[amarc]

https://hg.mozilla.org/mozilla-central/rev/79c680d8be01

Comment 16

[Mira Lobontiu (Android QA)]

Verified as fixed on the Firefox for Android 147.0.1 build, and on the latest Firefox for Android Nightly 149.0a1 from 1/16, with the following devices:

• Samsung Galaxy S22 Ultra (Android 16),
• Xiaomi Redmi9C NFC (Android 10),
• Honor Magic V2 (Android 14),
• Samsung Galaxy S24 Ultra (Android 16).

ChatGPT is working with both Studies ON or OFF.

Comment 17

[Mihai Boldan, Desktop QA [:mboldan]]

Reproduced on Firefox 147 RC, under Ubuntu 24.
The issue is no longer reproducible on Firefox 147.0.1, Firefox 148.0b3(treeherder build), or on Firefox 149.0a1 (2026-01-16)(treeherder build).
Tests were performed under Ubuntu 24.04, Windows 11 and macOS 10.15.

Comment 18

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/db30ed336471

Comment 19

[Randell Jesup [:jesup] (needinfo me)]

Note for reference that over the weekend they appear to have disabled compression dictionaries, so reproducing this bug will be tricky. The same issue affected particular flows in Shopify checkout and that still can be reproduced