883014 - Session store _collectTabData assumes about:blank has a document.body

Status: RESOLVED DUPLICATE of bug 973550

(Firefox :: Session Restore, defect)

Description

[Jesse Ruderman]

Attachment: testcase

1. Set:
     user_pref("media.webm.enabled", false);
2. Load the testcase
3. Click the button
4. Watch the Browser Console (or stdout / stderr in a debug build)

Result:

[Exception... "'[JavaScript Error: "browser.contentDocument.body is null" {file: "resource:///modules/sessionstore/SessionStore.jsm" line: 1910}]' when calling method: [nsIObserver::observe]"  nsresult: "0x80570021 (NS_ERROR_XPC_JAVASCRIPT_ERROR_WITH_DETAILS)"  location: "native frame :: <unknown filename> :: <TOP_LEVEL> :: line 0"  data: yes]

>    else if (browser.currentURI.spec != "about:blank" ||
>             browser.contentDocument.body.hasChildNodes()) {

Comment 1

[Tim Taubert [:ttaubert] (inactive)]

I can't reproduce the error in my trunk build. Is it still reproducible for you?

Comment 2

[Jesse Ruderman]

Yes, I can still reproduce with https://ftp.mozilla.org/pub/mozilla.org/firefox/tinderbox-builds/mozilla-central-macosx64-debug/1373658654/ built from http://hg.mozilla.org/mozilla-central/rev/3433a021847b

Sometimes I have to wait a second or two for the exception.  Setting a second pref seems to help:

  user_pref("media.webm.enabled", false);
  user_pref("browser.sessionstore.resume_from_crash", false);

Comment 3

[Jesse Ruderman]

Now I get:

System JS : ERROR resource://app/modules/sessionstore/SessionHistory.jsm:121 - TypeError: webNavigation.document.body is null

(a different error in a different file)

Maybe this morphed into bug 973550?

Comment 4

[Tim Taubert [:ttaubert] (inactive)]

Indeed it did. Let's fix it there.