After updating firefox,
firebug not showing the console errors always. It shows while firefox starts, and then doing the debug once or twice stops the error messages in console, also the debug does not always take you to the point where the debugger stopped.
You will have to activate the debugger once again with an addition breakpoint, when the debugger is activated .
Also, there was a good feature in that I was able to do with 26 firefox version, cancel the debug using (redo icon).
I don't see this icon anymore.