Bug: Intermittent toolkit/components/nimbus/test/browser/browser_nimbus_telemetry.js | A promise chain failed to handle a rejection: An experiment with the slug "foo1615291706075" already exists. - stack: enroll@resource://nimbus/lib/ExperimentManager.jsm:197
Status: RESOLVED
Priority: P5
Resolution: FIXED
Created: 2021-03-09 13:22:06+00:00
Resolved: 2021-06-01 14:55:01+00:00

**Filed by:** ncsoregi [at] mozilla.com
**Parsed log:** https://treeherder.mozilla.org/logviewer?job_id=332516905&repo=mozilla-central
**Full log:** https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/T0hmq4DMTzSN--EIOv7pEQ/runs/0/artifacts/public/logs/live_backing.log

---
```
[task 2021-03-09T12:08:26.244Z] 12:08:26     INFO - TEST-PASS | toolkit/components/nimbus/test/browser/browser_nimbus_telemetry.js | extra[featureId] must match in event normandy#expose#nimbus_experiment. - "test-feature" matches "test-feature" - 
[task 2021-03-09T12:08:26.245Z] 12:08:26     INFO - Leaving test bound test_experiment_expose_Telemetry
[task 2021-03-09T12:08:26.245Z] 12:08:26     INFO - Console message: [JavaScript Error: "No manifest entry for test-feature. Please add one to toolkit/components/messaging-system/experiments/ExperimentAPI.jsm" {file: "resource://nimbus/ExperimentAPI.jsm" line: 326}]
[task 2021-03-09T12:08:26.245Z] 12:08:26     INFO - ExperimentFeature@resource://nimbus/ExperimentAPI.jsm:326:10
[task 2021-03-09T12:08:26.245Z] 12:08:26     INFO - test_experiment_expose_Telemetry@chrome://mochitests/content/browser/toolkit/components/nimbus/test/browser/browser_nimbus_telemetry.js:132:19
[task 2021-03-09T12:08:26.246Z] 12:08:26     INFO - 
[task 2021-03-09T12:08:26.246Z] 12:08:26     INFO - Console message: [JavaScript Error: "Error: An experiment with the slug "foo1615291706075" already exists." {file: "resource://nimbus/lib/ExperimentManager.jsm" line: 197}]
[task 2021-03-09T12:08:26.246Z] 12:08:26     INFO - Buffered messages finished
[task 2021-03-09T12:08:26.249Z] 12:08:26     INFO - TEST-UNEXPECTED-FAIL | toolkit/components/nimbus/test/browser/browser_nimbus_telemetry.js | A promise chain failed to handle a rejection: An experiment with the slug "foo1615291706075" already exists. - stack: enroll@resource://nimbus/lib/ExperimentManager.jsm:197:13
[task 2021-03-09T12:08:26.250Z] 12:08:26     INFO - onRecipe@resource://nimbus/lib/ExperimentManager.jsm:115:18
[task 2021-03-09T12:08:26.250Z] 12:08:26     INFO - Rejection date: Tue Mar 09 2021 12:08:26 GMT+0000 (Greenwich Mean Time) - false == true - JS frame :: resource://testing-common/PromiseTestUtils.jsm :: assertNoUncaughtRejections :: line 285
[task 2021-03-09T12:08:26.250Z] 12:08:26     INFO - Stack trace:
[task 2021-03-09T12:08:26.250Z] 12:08:26     INFO - resource://testing-common/PromiseTestUtils.jsm:assertNoUncaughtRejections:285
[task 2021-03-09T12:08:26.250Z] 12:08:26     INFO - chrome://mochikit/content/browser-test.js:nextTest:631
[task 2021-03-09T12:08:26.251Z] 12:08:26     INFO - GECKO(2055) | MEMORY STAT | vsize 6929MB | residentFast 269MB | heapAllocated 107MB
[task 2021-03-09T12:08:26.251Z] 12:08:26     INFO - TEST-OK | toolkit/components/nimbus/test/browser/browser_nimbus_telemetry.js | took 66ms```