1741250 - Existing cfr experiment results in TypeError "target.features is undefined"

Status: VERIFIED FIXED

(Firefox :: Nimbus Desktop Client, defect)

Description

[Ed Lee :Mardak]

I happened to have force enrolled in cfr experiment before bug 1739666 landed, so this could be similar to someone already in a cfr experment in 95 then upgrading to 96?

TypeError: can't access property "find", target.features is undefined

https://searchfox.org/mozilla-central/rev/674b6582bafedc11fba6dc537769c88e9ed921d3/toolkit/components/nimbus/ExperimentAPI.jsm#73-80

Stack:

get@resource://nimbus/ExperimentAPI.jsm:80:40
_experimentsAPILoader@resource://activity-stream/lib/ASRouter.jsm:347:25

Where it seems to be trying to access…

// { slug: "optin-emotive-pin-firefox-modal", active: true, branch: Proxy }
let experimentData = ExperimentAPI.getExperiment({ featureId: "cfr" });

// { slug: "treatment-b", ratio: 1, feature: { value: {…}, enabled: true, featureId: "cfr" } }
experimentData.branch["cfr"]

So features doesn't exist on branch but there is a single feature

Comment 1

[Andrei Oprea [:andreio]]

Attachment: WIP: Bug 1741250 - Existing cfr experiment results in TypeError 'target.features is undefined'

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1739666

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/7f59824964b7
Existing cfr experiment results in TypeError 'target.features is undefined' r=k88hudson,Mardak

Comment 4

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/7f59824964b7

Comment 5

[Andrei Oprea [:andreio]]

Comment on attachment 9250807 [details]
WIP: Bug 1741250 - Existing cfr experiment results in TypeError 'target.features is undefined'

Beta/Release Uplift Approval Request

• User impact if declined: This regression break backwards compatibility for experiment recipes when users upgrade from 94 to 95 and could potentially impact any experiment that's live at that time.
• Is this code covered by automated tests?: Yes
• Has the fix been verified in Nightly?: No
• Needs manual test from QE?: Yes
• If yes, steps to reproduce: To confirm the fix you should force enroll into the test recipe from Staging test-tcp-rollout-experimenter-v3 in Firefox 94 then open the same profile in Firefox Nightly. Check in ASRouterAdmin that the recipe spotlight message is present as expected.
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Small change covered by testing. Only touches Nimbus code not a Firefox feature.
• String changes made/needed:

Comment 6

[Marius Coman [:mcoman], Ecosystem QA]

I have verified that this issue is no longer reproducible with the latest Firefox Nightly (94.0.1 Build ID - 20211103134640), and the latest Firefox Nightly (96.0a1 Build ID - 20211118034937) using the following steps:

1. Open the Firefox 94.0.1 Release browser.
2. Enroll in the "treatment" branch of the "Test TCP rollout experimenter" rollout.
3. Close the browser and open the same profile with the latest Firefox Nightly browser.
4. Navigate to the "about:newtab#devtools" page.
5. Observe the displayed messages.

After following the steps from above I can confirm that the "AS Router" page is successfully populated and the "test-tcp-rollout-experimenter:treatment" message is displayed.

Comment 7

[Pascal Chevrel:pascalc (PTO until April 26)]

Comment on attachment 9250807 [details]
WIP: Bug 1741250 - Existing cfr experiment results in TypeError 'target.features is undefined'

Low risk, approved for 95 beta 9, thanks.

Comment 8

[Pascal Chevrel:pascalc (PTO until April 26)]

https://hg.mozilla.org/releases/mozilla-beta/rev/849abb4b0e9e

Comment 9

[Marius Coman [:mcoman], Ecosystem QA]

I have verified that this issue is no longer reproducible with the latest Firefox Nightly (94.0.1 Build ID - 20211103134640), and the latest Firefox Beta (95.0b9 Build ID - 20211118185700) using the following steps:

Open the Firefox 94.0.1 Release browser.
Enroll in the "treatment" branch of the "Test TCP rollout experimenter" rollout.
Close the browser and open the same profile with the latest Firefox Nightly browser.
Navigate to the "about:newtab#devtools" page.
Observe the displayed messages.

After following the steps from above I can confirm that the "AS Router" page is successfully populated and the "test-tcp-rollout-experimenter:treatment" message is displayed.