STR: 1. Launch an older version of Firefox, such as an older Nightly installation. 2. Open the Menu - Help - About Firefox, check for update. 3. Once the update is pending for restart the browser, try to open the Browser Toolbox from Developer menu. Actual results: Pending updates will be installed, then a window appears with: Error opening Browser Toolbox: Component returned failure code: 0x804b000d (NS_ERROR_CONNECTION_REFUSED) [nsIInputStream.available] Expected results: a: Prevent the pending updates being installed, postponed until the next time. b: Correctly pass the required parameters, thereby normally opening.