Bug: Intermittent browser/components/downloads/test/browser/browser_about_downloads.js | Uncaught exception - at chrome://mochitests/content/browser/browser/components/downloads/test/browser/browser_about_downloads.js:38 - TypeError: can't a
Status: RESOLVED
Priority: P5
Resolution: FIXED
Created: 2020-02-22 02:09:34+00:00
Resolved: 2020-03-16 06:12:59+00:00

**Filed by:** btara [at] mozilla.com
**Parsed log:** https://treeherder.mozilla.org/logviewer.html#?job_id=289973531&repo=mozilla-central
**Full log:** https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/ddsa084kTeeJUMbGg9gdJA/runs/0/artifacts/public/logs/live_backing.log
**Reftest URL:** https://hg.mozilla.org/mozilla-central/raw-file/tip/layout/tools/reftest/reftest-analyzer.xhtml#logurl=https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/ddsa084kTeeJUMbGg9gdJA/runs/0/artifacts/public/logs/live_backing.log&only_show_unexpected=1

---

```
[task 2020-02-21T23:01:12.955Z] 23:01:12     INFO - TEST-START | browser/components/downloads/test/browser/browser_about_downloads.js
[task 2020-02-21T23:01:13.372Z] 23:01:13     INFO - TEST-INFO | started process screenshot
[task 2020-02-21T23:01:13.437Z] 23:01:13     INFO - TEST-INFO | screenshot: exit 0
[task 2020-02-21T23:01:13.437Z] 23:01:13     INFO - Buffered messages logged at 23:01:12
[task 2020-02-21T23:01:13.437Z] 23:01:13     INFO - Entering test bound test_about_downloads
[task 2020-02-21T23:01:13.437Z] 23:01:13     INFO - Buffered messages logged at 23:01:13
[task 2020-02-21T23:01:13.438Z] 23:01:13     INFO - TEST-PASS | browser/components/downloads/test/browser/browser_about_downloads.js | Should have list of downloads - [object XULElement] == true - 
[task 2020-02-21T23:01:13.438Z] 23:01:13     INFO - TEST-PASS | browser/components/downloads/test/browser/browser_about_downloads.js | Should have 2 downloads. - 2 == 2 - 
[task 2020-02-21T23:01:13.438Z] 23:01:13     INFO - TEST-PASS | browser/components/downloads/test/browser/browser_about_downloads.js | Label 'dm-ui-test.file' should match 'dm-ui-test.file' - true == true - 
[task 2020-02-21T23:01:13.438Z] 23:01:13     INFO - Buffered messages finished
[task 2020-02-21T23:01:13.438Z] 23:01:13     INFO - TEST-UNEXPECTED-FAIL | browser/components/downloads/test/browser/browser_about_downloads.js | Uncaught exception - at chrome://mochitests/content/browser/browser/components/downloads/test/browser/browser_about_downloads.js:38 - TypeError: can't access property "value", desc is null
[task 2020-02-21T23:01:13.438Z] 23:01:13     INFO - Stack trace:
[task 2020-02-21T23:01:13.438Z] 23:01:13     INFO - @chrome://mochitests/content/browser/browser/components/downloads/test/browser/browser_about_downloads.js:38:1
[task 2020-02-21T23:01:13.438Z] 23:01:13     INFO - execute@resource://specialpowers/SpecialPowersSandbox.jsm:140:12
[task 2020-02-21T23:01:13.438Z] 23:01:13     INFO - _spawnTask@resource://specialpowers/SpecialPowersChild.jsm:1727:15
[task 2020-02-21T23:01:13.438Z] 23:01:13     INFO - receiveMessage@resource://specialpowers/SpecialPowersChild.jsm:285:21
[task 2020-02-21T23:01:13.438Z] 23:01:13     INFO - JSWindowActor query*receiveMessage@resource://specialpowers/SpecialPowersParent.jsm:1055:12
[task 2020-02-21T23:01:13.438Z] 23:01:13     INFO - JSWindowActor query*spawn@resource://specialpowers/SpecialPowersChild.jsm:1682:17
[task 2020-02-21T23:01:13.438Z] 23:01:13     INFO - test_about_downloads/<@chrome://mochitests/content/browser/browser/components/downloads/test/browser/browser_about_downloads.js:28:25
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - async*withNewTab@resource://testing-common/BrowserTestUtils.jsm:150:24
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - async*test_about_downloads@chrome://mochitests/content/browser/browser/components/downloads/test/browser/browser_about_downloads.js:20:26
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - Async*Tester_execTest/<@chrome://mochikit/content/browser-test.js:1062:34
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - Tester_execTest@chrome://mochikit/content/browser-test.js:1097:11
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - nextTest/<@chrome://mochikit/content/browser-test.js:919:14
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - SimpleTest.waitForFocus/waitForFocusInner/focusedOrLoaded/<@chrome://mochikit/content/tests/SimpleTest/SimpleTest.js:914:23
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - Leaving test bound test_about_downloads
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - Console message: [JavaScript Error: "Win error 2 during operation open on file C:\Users\task_1582324979\AppData\Local\Temp\dm-ui-test.file (The system cannot find the file specified.
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - )" {file: "resource://gre/modules/DownloadCore.jsm" line: 125}]
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - isPlaceholder@resource://gre/modules/DownloadCore.jsm:125:8
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - async*removeData@resource://gre/modules/DownloadCore.jsm:2383:16
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - removePartialData/this._promiseRemovePartialData<@resource://gre/modules/DownloadCore.jsm:879:28
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - removePartialData@resource://gre/modules/DownloadCore.jsm:889:9
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - finalize@resource://gre/modules/DownloadCore.jsm:1038:19
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - task_resetState@chrome://mochitests/content/browser/browser/components/downloads/test/browser/head.js:79:20
[task 2020-02-21T23:01:13.439Z] 23:01:13     INFO - async*nextTest@chrome://mochikit/content/browser-test.js:570:35
[task 2020-02-21T23:01:13.440Z] 23:01:13     INFO - async*testScope/test_finish/<@chrome://mochikit/content/browser-test.js:1457:25
[task 2020-02-21T23:01:13.440Z] 23:01:13     INFO - run@chrome://mochikit/content/browser-test.js:1372:9
[task 2020-02-21T23:01:13.440Z] 23:01:13     INFO - 
[task 2020-02-21T23:01:13.440Z] 23:01:13     INFO - GECKO(4648) | MEMORY STAT | vsize 785MB | vsizeMaxContiguous 457MB | residentFast 254MB | heapAllocated 128MB
[task 2020-02-21T23:01:13.440Z] 23:01:13     INFO - TEST-OK | browser/components/downloads/test/browser/browser_about_downloads.js | took 438ms
[task 2020-02-21T23:01:13.440Z] 23:01:13     INFO - Not taking screenshot here: see the one that was previously logged
[task 2020-02-21T23:01:13.440Z] 23:01:13     INFO - TEST-UNEXPECTED-FAIL | browser/components/downloads/test/browser/browser_about_downloads.js | Found an unexpected tab at the end of test run: about:downloads - 
[task 2020-02-21T23:01:13.440Z] 23:01:13     INFO - checking window state
[task 2020-02-21T23:01:14.905Z] 23:01:14     INFO - GECKO(4648) | Completed ShutdownLeaks collections in process 2248
[task 2020-02-21T23:01:14.905Z] 23:01:14     INFO - GECKO(4648) | Completed ShutdownLeaks collections in process 1992
[task 2020-02-21T23:01:14.920Z] 23:01:14     INFO - GECKO(4648) | Completed ShutdownLeaks collections in process 6076
[task 2020-02-21T23:01:14.940Z] 23:01:14     INFO - GECKO(4648) | Completed ShutdownLeaks collections in process 4572
[task 2020-02-21T23:01:14.940Z] 23:01:14     INFO - GECKO(4648) | Completed ShutdownLeaks collections in process 5284
[task 2020-02-21T23:01:14.947Z] 23:01:14     INFO - GECKO(4648) | Completed ShutdownLeaks collections in process 4156
[task 2020-02-21T23:01:14.947Z] 23:01:14     INFO - GECKO(4648) | Completed ShutdownLeaks collections in process 4740
[task 2020-02-21T23:01:14.954Z] 23:01:14     INFO - GECKO(4648) | Completed ShutdownLeaks collections in process 1452
[task 2020-02-21T23:01:14.961Z] 23:01:14     INFO - GECKO(4648) | Completed ShutdownLeaks collections in process 1344
[task 2020-02-21T23:01:15.516Z] 23:01:15     INFO - GECKO(4648) | Completed ShutdownLeaks collections in process 3992
[task 2020-02-21T23:01:15.516Z] 23:01:15     INFO - TEST-START | Shutdown
...
...
```