Firefox Gmail Corrupted content error

Today, suddenly, my Firefox can not access Gmail. When I try to log in to my Gmail, it shows:

Damaged content error
The site at https://mail.google.com/mail/u/0/ has experienced a network protocol violation that can not be repaired.
The page you are trying to view can not be displayed because an error was detected in the data transmission.

I have tried to delete all the cache and cookies, and even start my Firefox in safe mode, I am still getting Damaged content error message when I connect to my Gmail account. However, I can access it when I open my Gmail in the private Firefox window.

What causes it? How can i fix it? Or do I have to switch to the Chrome browser to use Gmail?