Bug: Intermittent browser/components/newtab/test/browser/abouthomecache/browser_overwrite_cache.js | Found the target element - null == true - got null, expected true (operator ==)
Status: RESOLVED
Priority: P5
Resolution: FIXED
Created: 2020-06-27 00:55:40+00:00
Resolved: 2022-01-10 06:25:13+00:00

**Filed by:** malexandru [at] mozilla.com
**Parsed log:** https://treeherder.mozilla.org/logviewer.html#?job_id=307712883&repo=autoland
**Full log:** https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/KhlWYwHlSUCw6yiXhmAxcA/runs/0/artifacts/public/logs/live_backing.log

---

```
[task 2020-06-27T00:23:23.378Z] 00:23:23     INFO - TEST-START | browser/components/newtab/test/browser/abouthomecache/browser_overwrite_cache.js
[task 2020-06-27T00:23:23.393Z] 00:23:23     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 070C2400 == 4 [pid = 1760] [id = {5e159bf3-5224-48b0-b146-267e43ced9a6}]
[task 2020-06-27T00:23:23.394Z] 00:23:23     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 20 (012F8340) [pid = 1760] [serial = 27] [outer = 00000000]
[task 2020-06-27T00:23:23.394Z] 00:23:23     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 21 (070CAC00) [pid = 1760] [serial = 28] [outer = 012F8340]
[task 2020-06-27T00:23:23.394Z] 00:23:23     INFO - GECKO(5720) | [Child 6056, Main Thread] WARNING: 'NS_FAILED(GetAccentColor(unused))', file /builds/worker/checkouts/gecko/widget/windows/nsLookAndFeel.cpp, line 485
[task 2020-06-27T00:23:23.449Z] 00:23:23     INFO - GECKO(5720) | [Parent 4212, Main Thread] WARNING: NS_ENSURE_TRUE(GetWrapper()) failed: file /builds/worker/checkouts/gecko/dom/ipc/JSActor.cpp, line 90
[task 2020-06-27T00:23:23.484Z] 00:23:23     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 22 (0EBED800) [pid = 1760] [serial = 29] [outer = 012F8340]
[task 2020-06-27T00:23:23.611Z] 00:23:23     INFO - GECKO(5720) | ### XPCOM_MEM_BLOAT_LOG defined -- logging bloat/leaks to c:\users\task_1593216383\appdata\local\temp\tmpdakzwj.mozrunner\runtests_leaks_tab_pid1348.log
[task 2020-06-27T00:23:23.611Z] 00:23:23     INFO - GECKO(5720) | [1348, Main Thread] WARNING: XPCOM_MEM_BLOAT_LOG is set, disabling native allocations.: file /builds/worker/checkouts/gecko/tools/profiler/core/platform.cpp, line 244
[task 2020-06-27T00:23:24.071Z] 00:23:24     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 23 (118AC800) [pid = 1760] [serial = 30] [outer = 012F8340]
[task 2020-06-27T00:23:24.086Z] 00:23:24     INFO - GECKO(5720) | [Child 1760, Main Thread] WARNING: NS_ENSURE_TRUE(!mHasOrHasHadOwnerWindow || mOwnerWindow) failed: file /builds/worker/checkouts/gecko/dom/events/DOMEventTargetHelper.cpp, line 291
[task 2020-06-27T00:23:25.273Z] 00:23:25     INFO - GECKO(5720) | [Child 4600: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 8 (0A033C00) [pid = 4600] [serial = 13] [outer = 00000000] [url = moz-extension://b22b2757-97d7-42d9-a5a4-f798cb670948/_generated_background_page.html]
[task 2020-06-27T00:23:25.309Z] 00:23:25     INFO - GECKO(5720) | [Child 5656: Main Thread]: I/DocShellAndDOMWindowLeak --DOCSHELL 009A6C00 == 0 [pid = 5656] [id = {1467d25c-e674-41cb-9338-66df26da8d25}] [url = about:blank]
[task 2020-06-27T00:23:25.315Z] 00:23:25     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 22 (12390800) [pid = 1760] [serial = 20] [outer = 00000000] [url = about:home]
[task 2020-06-27T00:23:25.315Z] 00:23:25     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 21 (11844C00) [pid = 1760] [serial = 24] [outer = 00000000] [url = about:blank]
[task 2020-06-27T00:23:25.316Z] 00:23:25     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 20 (11A4D000) [pid = 1760] [serial = 12] [outer = 00000000] [url = about:home]
[task 2020-06-27T00:23:25.316Z] 00:23:25     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 19 (0EBF9C00) [pid = 1760] [serial = 11] [outer = 00000000] [url = about:home]
[task 2020-06-27T00:23:25.316Z] 00:23:25     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 18 (100C0400) [pid = 1760] [serial = 19] [outer = 00000000] [url = about:blank]
[task 2020-06-27T00:23:25.316Z] 00:23:25     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 17 (14172400) [pid = 1760] [serial = 16] [outer = 00000000] [url = about:home]
[task 2020-06-27T00:23:25.317Z] 00:23:25     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 16 (0B03C400) [pid = 1760] [serial = 10] [outer = 00000000] [url = about:home]
[task 2020-06-27T00:23:25.317Z] 00:23:25     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 15 (12306C00) [pid = 1760] [serial = 15] [outer = 00000000] [url = about:home]
[task 2020-06-27T00:23:25.317Z] 00:23:25     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 14 (0B0F0C00) [pid = 1760] [serial = 17] [outer = 00000000] [url = about:home]
[task 2020-06-27T00:23:25.317Z] 00:23:25     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 13 (0EBEA400) [pid = 1760] [serial = 7] [outer = 00000000] [url = about:blank]
[task 2020-06-27T00:23:25.318Z] 00:23:25     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 12 (070C1C00) [pid = 1760] [serial = 3] [outer = 00000000] [url = about:home]
[task 2020-06-27T00:23:25.358Z] 00:23:25     INFO - GECKO(5720) | [Child 1760: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 13 (0EB87800) [pid = 1760] [serial = 31] [outer = 012F8340]
[task 2020-06-27T00:23:25.578Z] 00:23:25     INFO - GECKO(5720) | [Child 1760, Main Thread] WARNING: NS_ENSURE_TRUE(!mHasOrHasHadOwnerWindow || mOwnerWindow) failed: file /builds/worker/checkouts/gecko/dom/events/DOMEventTargetHelper.cpp, line 291
[task 2020-06-27T00:23:25.896Z] 00:23:25     INFO - TEST-INFO | started process screenshot
[task 2020-06-27T00:23:25.958Z] 00:23:25     INFO - TEST-INFO | screenshot: exit 0
[task 2020-06-27T00:23:25.959Z] 00:23:25     INFO - Buffered messages logged at 00:23:23
[task 2020-06-27T00:23:25.959Z] 00:23:25     INFO - Entering test bound test_overwrite_cache
[task 2020-06-27T00:23:25.960Z] 00:23:25     INFO - Simulating restart of the browser
[task 2020-06-27T00:23:25.960Z] 00:23:25     INFO - Simulating shutdown write
[task 2020-06-27T00:23:25.960Z] 00:23:25     INFO - Console message: 1593217403780	AboutHomeStartupCache	TRACE	Never wrote a cache this session. Arming cache task.
[task 2020-06-27T00:23:25.961Z] 00:23:25     INFO - Console message: 1593217403781	AboutHomeStartupCache	TRACE	Finalizing cache task on shutdown
[task 2020-06-27T00:23:25.961Z] 00:23:25     INFO - Console message: 1593217403781	AboutHomeStartupCache	TRACE	Caching now.
[task 2020-06-27T00:23:25.961Z] 00:23:25     INFO - Console message: 1593217403781	AboutHomeStartupCache	TRACE	Parent is requesting Activity Stream state object.
[task 2020-06-27T00:23:25.961Z] 00:23:25     INFO - Console message: 1593217403781	AboutHomeStartupCache	TRACE	Parent received cache streams.
[task 2020-06-27T00:23:25.962Z] 00:23:25     INFO - Console message: 1593217403880	AboutHomeStartupCache	TRACE	Parent received cache streams.
[task 2020-06-27T00:23:25.962Z] 00:23:25     INFO - Console message: 1593217403880	AboutHomeStartupCache	TRACE	Populating the cache. Dooming old entry.
[task 2020-06-27T00:23:25.962Z] 00:23:25     INFO - Console message: 1593217403880	AboutHomeStartupCache	TRACE	Clearing the cache.
[task 2020-06-27T00:23:25.963Z] 00:23:25     INFO - Console message: 1593217403880	AboutHomeStartupCache	TRACE	Opening the page output stream.
[task 2020-06-27T00:23:25.963Z] 00:23:25     INFO - Console message: 1593217403880	AboutHomeStartupCache	INFO	Writing the page cache.
[task 2020-06-27T00:23:25.963Z] 00:23:25     INFO - Console message: 1593217403882	AboutHomeStartupCache	TRACE	Writing the page data is complete. Now opening the script output stream.
[task 2020-06-27T00:23:25.964Z] 00:23:25     INFO - Console message: 1593217403882	AboutHomeStartupCache	INFO	Writing the script cache.
[task 2020-06-27T00:23:25.964Z] 00:23:25     INFO - Shutdown write done
[task 2020-06-27T00:23:25.965Z] 00:23:25     INFO - Waiting for AboutHomeStartupCacheChild to uninit
[task 2020-06-27T00:23:25.965Z] 00:23:25     INFO - Console message: 1593217403883	AboutHomeStartupCache	TRACE	Writing the script cache is done. Setting version.
[task 2020-06-27T00:23:25.966Z] 00:23:25     INFO - Console message: 1593217403884	AboutHomeStartupCache	TRACE	Version is set to 20200626234540.
<...>
[task 2020-06-27T00:23:25.982Z] 00:23:25     INFO - AboutHomeStartupCacheChild uninitted
[task 2020-06-27T00:23:25.982Z] 00:23:25     INFO - Waiting for AboutHomeStartupCache cache entry
[task 2020-06-27T00:23:25.982Z] 00:23:25     INFO - Got AboutHomeStartupCache cache entry
[task 2020-06-27T00:23:25.983Z] 00:23:25     INFO - Waiting for about:home to load
[task 2020-06-27T00:23:25.983Z] 00:23:25     INFO - Console message: 1593217405297	AboutHomeStartupCache	TRACE	Initting.
[task 2020-06-27T00:23:25.984Z] 00:23:25     INFO - Console message: 1593217405297	AboutHomeStartupCache	TRACE	Cache entry is available.
[task 2020-06-27T00:23:25.984Z] 00:23:25     INFO - Console message: 1593217405297	AboutHomeStartupCache	TRACE	Constructing pipes.
[task 2020-06-27T00:23:25.984Z] 00:23:25     INFO - Console message: 1593217405297	AboutHomeStartupCache	TRACE	
[task 2020-06-27T00:23:25.985Z] 00:23:25     INFO - Console message: 1593217405297	AboutHomeStartupCache	INFO	Version retrieved is: 20200626234540
[task 2020-06-27T00:23:25.985Z] 00:23:25     INFO - Console message: 1593217405298	AboutHomeStartupCache	TRACE	Connecting page stream to pipe.
[task 2020-06-27T00:23:25.986Z] 00:23:25     INFO - Console message: 1593217405298	AboutHomeStartupCache	TRACE	Connecting script stream to pipe.
[task 2020-06-27T00:23:25.986Z] 00:23:25     INFO - Console message: 1593217405298	AboutHomeStartupCache	TRACE	Streams connected to pipes. Dropping references to pipes.
[task 2020-06-27T00:23:25.986Z] 00:23:25     INFO - Console message: 1593217405299	AboutHomeStartupCache	TRACE	Initialized.
[task 2020-06-27T00:23:25.987Z] 00:23:25     INFO - Console message: 1593217405299	AboutHomeStartupCache	TRACE	Constructing pipes.
[task 2020-06-27T00:23:25.987Z] 00:23:25     INFO - Console message: 1593217405299	AboutHomeStartupCache	INFO	Sending input streams down to content process.
[task 2020-06-27T00:23:25.987Z] 00:23:25     INFO - Console message: 1593217405299	AboutHomeStartupCache	TRACE	The cache entry is already available. Connecting to pipes immediately.
[task 2020-06-27T00:23:25.988Z] 00:23:25     INFO - Console message: 1593217405299	AboutHomeStartupCache	TRACE	
[task 2020-06-27T00:23:25.988Z] 00:23:25     INFO - Console message: 1593217405299	AboutHomeStartupCache	INFO	Version retrieved is: 20200626234540
[task 2020-06-27T00:23:25.988Z] 00:23:25     INFO - Console message: 1593217405300	AboutHomeStartupCache	TRACE	Connecting page stream to pipe.
[task 2020-06-27T00:23:25.989Z] 00:23:25     INFO - Console message: 1593217405300	AboutHomeStartupCache	TRACE	Connecting script stream to pipe.
[task 2020-06-27T00:23:25.989Z] 00:23:25     INFO - Console message: 1593217405300	AboutHomeStartupCache	TRACE	Streams connected to pipes. Dropping references to pipes.
[task 2020-06-27T00:23:25.990Z] 00:23:25     INFO - Console message: 1593217405309	AboutHomeStartupCache	INFO	Script stream connected to pipe.
[task 2020-06-27T00:23:25.990Z] 00:23:25     INFO - Console message: 1593217405309	AboutHomeStartupCache	INFO	Page stream connected to pipe.
[task 2020-06-27T00:23:25.991Z] 00:23:25     INFO - Console message: 1593217405309	AboutHomeStartupCache	INFO	Page stream connected to pipe.
[task 2020-06-27T00:23:25.991Z] 00:23:25     INFO - Console message: 1593217405311	AboutHomeStartupCache	INFO	Script stream connected to pipe.
[task 2020-06-27T00:23:25.991Z] 00:23:25     INFO - about:home loaded
[task 2020-06-27T00:23:25.992Z] 00:23:25     INFO - Buffered messages finished
[task 2020-06-27T00:23:25.992Z] 00:23:25     INFO - TEST-UNEXPECTED-FAIL | browser/components/newtab/test/browser/abouthomecache/browser_overwrite_cache.js | Found the target element - null == true - got null, expected true (operator ==)
[task 2020-06-27T00:23:25.992Z] 00:23:25     INFO - Stack trace:
[task 2020-06-27T00:23:25.992Z] 00:23:25     INFO - @chrome://mochitests/content/browser/browser/components/newtab/test/browser/abouthomecache/browser_overwrite_cache.js:35:14
[task 2020-06-27T00:23:25.992Z] 00:23:25     INFO - execute@resource://specialpowers/SpecialPowersSandbox.jsm:141:12
[task 2020-06-27T00:23:25.992Z] 00:23:25     INFO - _spawnTask@resource://specialpowers/SpecialPowersChild.jsm:1812:15
[task 2020-06-27T00:23:25.992Z] 00:23:25     INFO - receiveMessage@resource://specialpowers/SpecialPowersChild.jsm:318:21
[task 2020-06-27T00:23:25.993Z] 00:23:25     INFO - Leaving test bound test_overwrite_cache
[task 2020-06-27T00:23:25.993Z] 00:23:25     INFO - GECKO(5720) | [Child 1760, Main Thread] WARNING: NS_ENSURE_TRUE(!mHasOrHasHadOwnerWindow || mOwnerWindow) failed: file /builds/worker/checkouts/gecko/dom/events/DOMEventTargetHelper.cpp, line 291
[task 2020-06-27T00:23:25.993Z] 00:23:25     INFO - GECKO(5720) | MEMORY STAT | vsize 855MB | vsizeMaxContiguous 369MB | residentFast 277MB | heapAllocated 96MB
[task 2020-06-27T00:23:25.993Z] 00:23:25     INFO - TEST-OK | browser/components/newtab/test/browser/abouthomecache/browser_overwrite_cache.js | took 2593ms
```