Firefox Web Console Disabled?

Question

This happens when the page itself defines a global variable called console, for example. If the page is browser-sniffing to decide whether to define it, the behavior could differ in different browsers.

In the case of Firefox it also happens when Firebug is installed and its console is enabled, since that overrides the default window.console.

I had the same exact error message, and once I removed firebug, it went away.

I'm not saying you should remove firebug, I love firebug, but that is most probably the source of the error for you as well. One more note, the error was still there even if firebug was turned off (disabled) for that particular page.

Here is a JavaScript workaround I used to restore console API after it was set to empty function by a script on the page (works in Firefox 46, tested in Firebug and in greasemonkey script):

function restoreConsole() {
    var i = document.createElement('iframe');
    i.style.display = 'none';
    document.body.appendChild(i);
    window.console = i.contentWindow.console;
    i.parentNode.removeChild(i);
}

More info and credentials: Restoring console.log()

Right click over firebug console tab and uncheck "enabled" option (the first one).