Bug: Intermittent browser/components/sessionstore/test/browser_formdata.js | Uncaught exception - at /browser/components/sessionstore/test/browser_formdata.js:48 - TypeError: can't access property 0, formdata.children is undefined
Status: RESOLVED
Priority: P3
Resolution: FIXED
Created: 2021-04-07 22:03:33+00:00
Resolved: 2021-06-28 06:04:49+00:00

**Filed by:** apavel [at] mozilla.com
**Parsed log:** https://treeherder.mozilla.org/logviewer?job_id=335754150&repo=autoland
**Full log:** https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/MabWsanoRmitxAiqW8eDFg/runs/0/artifacts/public/logs/live_backing.log

---
```
[task 2021-04-07T21:18:18.594Z] 21:18:18     INFO - TEST-START | browser/components/sessionstore/test/browser_formdata.js
[task 2021-04-07T21:18:18.630Z] 21:18:18     INFO - GECKO(7216) | [Child 10565: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 2 (7f254ae63c80) [pid = 10565] [serial = 1] [outer = 0] [url = http://example.com/]
[task 2021-04-07T21:18:18.630Z] 21:18:18     INFO - GECKO(7216) | [Child 10565: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 1 (7f2534992800) [pid = 10565] [serial = 2] [outer = 0] [url = about:blank]
[task 2021-04-07T21:18:18.630Z] 21:18:18     INFO - GECKO(7216) | [Child 10565: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 0 (7f2534999800) [pid = 10565] [serial = 3] [outer = 0] [url = http://example.com/]
[task 2021-04-07T21:18:18.630Z] 21:18:18     INFO - GECKO(7216) | [Child 10565, Main Thread] WARNING: Extra shutdown CC: 'i < NORMAL_SHUTDOWN_COLLECTIONS', file /builds/worker/checkouts/gecko/xpcom/base/nsCycleCollector.cpp:3361
[task 2021-04-07T21:18:18.634Z] 21:18:18     INFO - GECKO(7216) | [Child 10565, Main Thread] WARNING: '!obs', file /builds/worker/checkouts/gecko/toolkit/components/sessionstore/RestoreTabContentObserver.cpp:58
[task 2021-04-07T21:18:18.635Z] 21:18:18     INFO - GECKO(7216) | [Child 10609: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f608e299400 == 1 [pid = 10609] [id = 0]
[task 2021-04-07T21:18:18.636Z] 21:18:18     INFO - GECKO(7216) | [Child 10609: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 1 (7f60a4763c80) [pid = 10609] [serial = 1] [outer = 0]
[task 2021-04-07T21:18:18.638Z] 21:18:18     INFO - GECKO(7216) | [Child 10609: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 2 (7f608e29a400) [pid = 10609] [serial = 2] [outer = 7f60a4763c80]
[task 2021-04-07T21:18:18.680Z] 21:18:18     INFO - GECKO(7216) | [Child 10565, Main Thread] WARNING: NS_ENSURE_TRUE(Preferences::InitStaticMembers()) failed: file /builds/worker/checkouts/gecko/modules/libpref/Preferences.cpp:4442
[task 2021-04-07T21:18:18.803Z] 21:18:18     INFO - GECKO(7216) | [Child 9455: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 4 (7fd43a919580) [pid = 9455] [serial = 26] [outer = 0] [url = about:newtab]
[task 2021-04-07T21:18:18.819Z] 21:18:18     INFO - GECKO(7216) | [Child 10609, Main Thread] WARNING: NS_ENSURE_TRUE(info) failed: file /builds/worker/checkouts/gecko/extensions/permissions/PermissionDelegateHandler.cpp:348
[task 2021-04-07T21:18:18.820Z] 21:18:18     INFO - GECKO(7216) | [Child 10609: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 3 (7f60880b7400) [pid = 10609] [serial = 3] [outer = 7f60a4763c80]
[task 2021-04-07T21:18:18.904Z] 21:18:18     INFO - GECKO(7216) | ### XPCOM_MEM_BLOAT_LOG defined -- logging bloat/leaks to /tmp/tmpi4NiA6.mozrunner/runtests_leaks_tab_pid10697.log
[task 2021-04-07T21:18:18.905Z] 21:18:18     INFO - GECKO(7216) | [10697, Main Thread] WARNING: XPCOM_MEM_BLOAT_LOG is set, disabling native allocations.: file /builds/worker/checkouts/gecko/tools/profiler/core/platform.cpp:254
[task 2021-04-07T21:18:18.982Z] 21:18:18     INFO - GECKO(7216) | [Child 10697, Main Thread] WARNING: could not set real-time limit in CubebUtils::InitLibrary: file /builds/worker/checkouts/gecko/dom/media/CubebUtils.cpp:619
[task 2021-04-07T21:18:19.111Z] 21:18:19     INFO - GECKO(7216) | [Child 10609: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f60880be800 == 2 [pid = 10609] [id = 1]
[task 2021-04-07T21:18:19.111Z] 21:18:19     INFO - GECKO(7216) | [Child 10609: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 4 (7f60a4763e40) [pid = 10609] [serial = 4] [outer = 0]
[task 2021-04-07T21:18:19.112Z] 21:18:19     INFO - GECKO(7216) | [Child 10609: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 5 (7f60880c0000) [pid = 10609] [serial = 5] [outer = 7f60a4763e40]
[task 2021-04-07T21:18:19.177Z] 21:18:19     INFO - GECKO(7216) | [Child 10614: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f1e93c96400 == 1 [pid = 10614] [id = 0]
[task 2021-04-07T21:18:19.178Z] 21:18:19     INFO - GECKO(7216) | [Child 10614: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 1 (7f1eaa163c80) [pid = 10614] [serial = 1] [outer = 0]
[task 2021-04-07T21:18:19.179Z] 21:18:19     INFO - GECKO(7216) | [Child 10614: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 2 (7f1e93c97400) [pid = 10614] [serial = 2] [outer = 7f1eaa163c80]
[task 2021-04-07T21:18:19.218Z] 21:18:19     INFO - GECKO(7216) | [Child 10614: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 3 (7f1e8dab6800) [pid = 10614] [serial = 3] [outer = 7f1eaa163c80]
[task 2021-04-07T21:18:19.420Z] 21:18:19     INFO - GECKO(7216) | [Child 10282: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 11 (7f0cea8a4800) [pid = 10282] [serial = 29] [outer = 0] [url = data:text/html;charset=utf-8,<iframe name=t src='data:text/html,A'></iframe><a id=lnk href='data:text/html,B' target=t>clickme</a><script>var i=document.createElement('iframe');i.setAttribute('src', 'data:text/html,C');document.body.appendChild(i);</script>]
[task 2021-04-07T21:18:19.420Z] 21:18:19     INFO - GECKO(7216) | [Child 10282: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 10 (7f0cea8a9400) [pid = 10282] [serial = 32] [outer = 0] [url = data:text/html,A]
[task 2021-04-07T21:18:19.420Z] 21:18:19     INFO - GECKO(7216) | [Child 10282: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 9 (7f0ceb6be400) [pid = 10282] [serial = 33] [outer = 0] [url = data:text/html,C]
[task 2021-04-07T21:18:19.420Z] 21:18:19     INFO - GECKO(7216) | [Child 10282: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 8 (7f0ceb6ca400) [pid = 10282] [serial = 34] [outer = 0] [url = data:text/html,B]
[task 2021-04-07T21:18:19.422Z] 21:18:19     INFO - GECKO(7216) | [Child 10282: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 7 (7f0ceb6ccc00) [pid = 10282] [serial = 39] [outer = 0] [url = about:blank]
[task 2021-04-07T21:18:19.425Z] 21:18:19     INFO - GECKO(7216) | [Child 10282: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 6 (7f0cea8a4c00) [pid = 10282] [serial = 38] [outer = 0] [url = about:blank]
[task 2021-04-07T21:18:19.425Z] 21:18:19     INFO - GECKO(7216) | [Child 10282: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 5 (7f0cea8a1000) [pid = 10282] [serial = 36] [outer = 0] [url = about:blank]
[task 2021-04-07T21:18:19.426Z] 21:18:19     INFO - GECKO(7216) | [Child 10282: Main Thread]: I/DocShellAndDOMWindowLeak --DOCSHELL 7f0cea89c400 == 1 [pid = 10282] [id = 16] [url = about:blank]
[task 2021-04-07T21:18:19.502Z] 21:18:19     INFO - GECKO(7216) | [Child 10282: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 4 (7f0cea807200) [pid = 10282] [serial = 40] [outer = 0] [url = about:blank]
[task 2021-04-07T21:18:19.503Z] 21:18:19     INFO - GECKO(7216) | [Child 10614: Main Thread]: I/DocShellAndDOMWindowLeak ++DOCSHELL 7f1e8dabd800 == 2 [pid = 10614] [id = 1]
[task 2021-04-07T21:18:19.503Z] 21:18:19     INFO - GECKO(7216) | [Child 10614: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 4 (7f1e8d13f040) [pid = 10614] [serial = 4] [outer = 0]
[task 2021-04-07T21:18:19.510Z] 21:18:19     INFO - GECKO(7216) | [Child 10614: Main Thread]: I/DocShellAndDOMWindowLeak ++DOMWINDOW == 5 (7f1e8dabf000) [pid = 10614] [serial = 5] [outer = 7f1e8d13f040]
[task 2021-04-07T21:18:19.560Z] 21:18:19     INFO - GECKO(7216) | [Child 7280: Main Thread]: I/DocShellAndDOMWindowLeak --DOMWINDOW == 2 (7fb1feac5000) [pid = 7280] [serial = 333] [outer = 0] [url = about:blank]
[task 2021-04-07T21:18:19.576Z] 21:18:19     INFO - GECKO(7216) | [Child 7280: Main Thread]: I/DocShellAndDOMWindowLeak --DOCSHELL 7fb1feabd400 == 0 [pid = 7280] [id = 152] [url = about:blank]
[task 2021-04-07T21:18:19.654Z] 21:18:19     INFO - GECKO(7216) | updateSessionStoreFromTablistener() with aData.sHistoryNeeded, but no SHlistener. Add again!!!JavaScript error: resource:///modules/sessionstore/SessionStore.jsm, line 1091: Error: no SessionHistory object
[task 2021-04-07T21:18:19.654Z] 21:18:19     INFO - GECKO(7216) | [Parent 7216, Main Thread] WARNING: NS_ENSURE_SUCCESS(rv, mozilla::ipc::IPCResult::Ok()) failed with result 0x80570021 (NS_ERROR_XPC_JAVASCRIPT_ERROR_WITH_DETAILS): file /builds/worker/checkouts/gecko/dom/ipc/BrowserParent.cpp:2918
[task 2021-04-07T21:18:19.655Z] 21:18:19     INFO - TEST-INFO | started process screentopng
[task 2021-04-07T21:18:20.055Z] 21:18:20     INFO - TEST-INFO | screentopng: exit 0
[task 2021-04-07T21:18:20.055Z] 21:18:20     INFO - Buffered messages logged at 21:18:18
[task 2021-04-07T21:18:20.055Z] 21:18:20     INFO - Entering test bound test_formdata
[task 2021-04-07T21:18:20.055Z] 21:18:20     INFO - Buffered messages logged at 21:18:19
[task 2021-04-07T21:18:20.055Z] 21:18:20     INFO - TEST-PASS | browser/components/sessionstore/test/browser_formdata.js | outer value is correct - 
[task 2021-04-07T21:18:20.055Z] 21:18:20     INFO - Buffered messages finished
[task 2021-04-07T21:18:20.055Z] 21:18:20     INFO - TEST-UNEXPECTED-FAIL | browser/components/sessionstore/test/browser_formdata.js | Uncaught exception - at chrome://mochitests/content/browser/browser/components/sessionstore/test/browser_formdata.js:48 - TypeError: can't access property 0, formdata.children is undefined
[task 2021-04-07T21:18:20.055Z] 21:18:20     INFO - Stack trace:
[task 2021-04-07T21:18:20.055Z] 21:18:20     INFO - test_formdata@chrome://mochitests/content/browser/browser/components/sessionstore/test/browser_formdata.js:48:3
[task 2021-04-07T21:18:20.055Z] 21:18:20     INFO - Leaving test bound test_formdata```