Question Youtube blocking my browser when login into my Google Account

[aor999]

Hello:
Today, whatever I log into my Youtube Account, I get the following error:

I refreshing the page and login, but:

This repeating every time I login into my youtube account.
How I get rid of this?

 

[rgd1101]

firefox look old. update to the latest

 

[aor999]

Firefox is 77.0.1 (64-bit)

 

[rgd1101]

try turn off all extension.

 

[aor999]

1. Turning off all extension solves the problem.
2. Turning off only the extension "Youtube Classic", which restores Youtube Classic Interface, solves this problem as well.

So it seems that Youtube blocks users that forces Youtube to load their classic interface.