User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101206 Ubuntu/10.10 (maverick) Firefox/3.6.13 Build Identifier: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:2.0b7) Gecko/20100101 Firefox/4.0b7 Error: this._browser is null Source File: chrome://global/content/bindings/findbar.xml Line: 1718 I find this happens when I cause these commands to run just after opening Firefox 4, any further attempts to run it works fine. This is either via the edit menu, keyboard short cut, or an extension that makes toolbar buttons of them. Reproducible: Always Steps to Reproduce: 1. Restart Firefox 2. Press ctrl + g 3. Open error console to see error, find bar will not open Actual Results: Error and find bar does not open. Expected Results: Find bar should open.

Confirmed using Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b9pre) Gecko/20101215 Firefox/4.0b9pre ID:20101215030322 Note: Only recent nightly builds show the error console message, for older builds, the find bar fails to show but no error message is shown in the console. Last good nightly: 2010-05-19 First bad nightly: 2010-05-20 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=145123f19ced&tochange=8d6db7f8fe09 Suspect: http://hg.mozilla.org/mozilla-central/rev/046c2d2acd3b Asaf Romano — Bug 566736 - Lazily initialize the findbar. r=gavin. Provisionally adding blocking bug 566736. Likely related to bug 567306.

Looks like if you just wait long enough then it works. Not ideal but I wouldn't block on it.