J’ai donc eu l’erreur suivante sur le plugin Jetpack : Uncaught Error: Class ‘Automattic\Jetpack\Roles’ .

Dans le détails :

WordPress version 5.3
Thème actuel : Twenty Eleven (version 3.3)
Extension actuelle : Jetpack by WordPress.com (version 8.0)
PHP version 7.2.25

Une erreur de type E_ERROR a été causée dans la ligne 270 du fichier .../wp-content/plugins/jetpack/vendor/automattic/jetpack-sync/src/Listener.php. Message d’erreur : Uncaught Error: Class 'Automattic\Jetpack\Roles' not found in .../wp-content/plugins/jetpack/vendor/automattic/jetpack-sync/src/Listener.php:270
Stack trace:
#0 .../wp-content/plugins/jetpack/vendor/automattic/jetpack-sync/src/Listener.php(239): Automattic\Jetpack\Sync\Listener->get_actor('jetpack_plugins...', Array)
#1 .../wp-content/plugins/jetpack/vendor/automattic/jetpack-sync/src/Listener.php(114): Automattic\Jetpack\Sync\Listener->enqueue_action('jetpack_plugins...', Array, Object(Automattic\Jetpack\Sync\Queue))
#2 .../wp-includes/class-wp-hook.php(288): Automattic\Jetpack\Sync\Listener->action_handler(Array, Array)
#3 .../wp-includes/class-wp-hook.php(312): WP_Hook->apply_filters('', Array)
#4 .../wp-includes/plugin.php(478): WP_Hook->do_action(Array)
#5 ....

Rien de grave si on lit : https://wordpress.org/support/topic/fatal-error-when-updating-to-jetpack-8-0-read-this/ .

The error may have been sent to you via an email with the subject line “Your Site is Experiencing a Technical Issue”, or it may have displayed in the Plugins page when you tried to update Jetpack.

This happened because we moved some files around in this Jetpack release, which triggers an error when they cannot be found in their old locations. Your site should still have upgraded to Jetpack 8.0, so refreshing the Plugins page in your dashboard should show that version. The error should only happen once, on upgrade, and not after that

As for the frontend of the site, that should also work fine, though you may want to clear any caches you have just to be sure.