Can’t reach admin page

Suddenly, as of <2 hours, I can’t reach my WP admin pages on Firefox, but they work fine in Chrome. I’ve cleared the Firefox cache and restarted the browser, with no luck.

The error is:

Warning: Invalid argument supplied for foreach() in /home/SITE/public_html/wp-content/plugins/jetpack/_inc/lib/admin-pages/class-jetpack-about-page.php on line 97

You attempted to access the “SITE” dashboard, but you do not currently have privileges on this site. If you believe you should be able to access the “SITE” dashboard, please contact your network administrator.