These days Firefox Nightly hardly usable, keeps crashing (you should expect this to happen, but a bit too much). Recently, Google sites showed small search boxes in Nightly, which is a Search giant’s bug, it has been fixed after some days.

How to block Third-Party Cookies in Chrome, Firefox and IE Browsers

Now, here is another one: when you try to sign into Gmail with Cookies enabled in Nightly, Gmail denies and shows the error ‘Oops! your browser seems to have cookies disabled. Make sure cookies are enabled or try opening a new browser window. Again, the fault or bug is on Google’s end, the fix is on the way and will land by tomorrow, if you can’t wait till then, follow the workaround mentioned below.

Gmail oops your browser has cookies disabled error

Read the latest changes happened in Nightly, from the below links

Fixing Gmail’s ‘Oops your browser seems to have Cookies disabled’ Error in Firefox Nightly

1. Visit about:config

2. Set  network.http.spdy.enabled.http2draft  preference value to false

3. Restart the browser, now try to sign into Gmail, you’ll, without any issues.

BTW, Gmail is working fine on Firefox 32.