Firefox, Win 7 when visiting gmail.. network protocol violation. What to file?

Question

Google

For a couple of weeks now, Firefox (Windows 7, latest updates), when visiting gmail, displays a white window with the text: "... https://mail.google.com/mail/u/0/#inbox , a network violation has occurred protocol that cannot be eliminated...". And so with several google boxes. Everything works on other pages of google sites. There are no problems with visiting mail.ru, ya.ru... or from a smartphone.
How to get rid of the problem without updating Firefox to the latest version?

Answer 1

Option:
about:serviceworkers in the address bar > https://mail.google.com > Check out.

Answer 2

Do a "reset Firefox" or create a new profile and transfer the necessary files (for example, with bookmarks) from the old one.

Answer 3

The situation corrected itself, after a few days again a violation. Then circle again. A few days pass and the situation changes.