User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1a3) Gecko/20060609 Firefox/1.5.0.4 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1a3) Gecko/20060609 Firefox/1.5.0.4 Every time, I open new Firefox window then Open up Error Console. I saw a warning. Reproducible: Always Steps to Reproduce: 1. Open Firefox 2. Go to error Console 3. You see a warning Actual Results: Error: uncaught exception: [Exception... "Component returned failure code: 0x80070057 (NS_ERROR_ILLEGAL_VALUE) [nsIPrefBranch2.addObserver]" nsresult: "0x80070057 (NS_ERROR_ILLEGAL_VALUE)" location: "JS frame :: chrome://global/content/bindings/tabbrowser.xml :: :: line 2269" data: no] Source file: chrome://global/content/bindings/tabbrowser.xml Line: 142 Expected Results: No more warning from Error Console.

*** This bug has been marked as a duplicate of 340547 ***