[Description:] The following reproduces only on a FF client when using a new non-existent preference added manually from about:config. [Prerequisites:] You need access to New Admin interface (https://normandy-admin.stage.mozaws.net/control-new) 1. Set the app.normandy.dev_mode preference to true to run recipes immediately on startup. 2. Set the app.normandy.logging.level preference to 0 to enable more logging. 3. Set the security.content.signature.root_hash preference to DB:74:CE:58:E4:F9:D0:9E:E0:42:36:BE:6C:C5:C4:F6:6A:E7:74:7D:C0:21:42:7A:03:BC:2F:57:0C:8B:9B:90. 4. Set the preference value for app.normandy.api_url set to https://normandy.stage.mozaws.net/api/v1 [Steps:] 1. Open Firefox client with a new profile. 2. Open about:config in a new tab and right click and add a new preferences: e.g. non_existent_preference, int, with value 10. 3. Open Admin center and create a new rollout type recipe, targeting the step2 preference, changing the value to something else, e.g. 12. 4. Publish step 3 recipe. 5. On the profile from step 1, set prerequisites and restart. 6. Open browser console and check the results. [Actual Result:] 1525337683826 app.normandy.recipe-runner INFO Executing recipe "pref-r-2" (action=preference-rollout) [Exception... "Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIPrefBranch.getIntPref]" nsresult: "0x8000ffff (NS_ERROR_UNEXPECTED)" location: "JS frame :: resource://normandy/lib/PrefUtils.jsm :: getPref :: line 34" data: no] getPref resource://normandy/lib/PrefUtils.jsm:34:16 _run/newRollout.preferences< resource://normandy/actions/PreferenceRolloutAction.jsm:41:24 map self-hosted:292:17 _run resource://normandy/actions/PreferenceRolloutAction.jsm:38:20 InterpretGeneratorResume self-hosted:1264:8 [Expected Result:] The preference rollout should be executed successfully with no browser console error.

Comment on attachment 8973029 [details] Bug 1458856 - Handle prefs with only a user value in preference rollout https://reviewboard.mozilla.org/r/241560/#review247390 Code analysis found 1 defect in this patch: - 1 defect found by mozlint You can run this analysis locally with: - `./mach lint path/to/file` (JS/Python) If you see a problem in this automated review, please report it here: http://bit.ly/2y9N9Vx ::: toolkit/components/normandy/lib/PrefUtils.jsm:46 (Diff revision 1) > } > + } catch (e) { > + if (branchName === "default" && e.result === Cr.NS_ERROR_UNEXPECTED) { > + // There is a value for the pref on the user branch but not on the default branch. This is ok. > + return defaultValue; > + } else { Error: Unnecessary 'else' after 'return'. [eslint: no-else-return]

Comment on attachment 8973029 [details] Bug 1458856 - Handle prefs with only a user value in preference rollout https://reviewboard.mozilla.org/r/241560/#review247516

Pushed by mcooper@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/b28e041ff83c Handle prefs with only a user value in preference rollout r=Gijs

Verified as fixed on the following builds: Beta 61.0b6(20180517141400) and Nightly 62.0a1(20180520220103). No error is displayed in browser console when a rollout is performed on a new non-existent preference.