Error

Hello,
Got this error when trying to delete a member !
Error Details
=============
An error of type E_ERROR was caused in line 678 of the file /var/www/html/wp-content/plugins/w3-total-cache/ObjectCache_WpObjectCache_Regular.php. Error message: Uncaught Error: Object of class stdClass could not be converted to string in /var/www/html/wp-content/plugins/w3-total-cache/ObjectCache_WpObjectCache_Regular.php:678
Stack trace:
#0 /var/www/html/wp-content/plugins/w3-total-cache/ObjectCache_WpObjectCache_Regular.php(139): W3TC\ObjectCache_WpObjectCache_Regular->_get_cache_key()
#1 /var/www/html/wp-content/plugins/w3-total-cache/ObjectCache_WpObjectCache_Regular.php(341): W3TC\ObjectCache_WpObjectCache_Regular->get()
#2 /var/www/html/wp-content/plugins/w3-total-cache/ObjectCache_WpObjectCache.php(63): W3TC\ObjectCache_WpObjectCache_Regular->delete()
#3 /var/www/html/wp-content/object-cache.php(80): W3TC\ObjectCache_WpObjectCache->delete()
#4 /var/www/html/wp-content/plugins/buddyboss-platform/bp-activity/bp-activity-cache.php(149): wp_cache_delete()
#5 /var/www/html/wp-includes/class-wp-hook.php(287): bp_activity_follow_delete_follow_ids_object_cache()
#6 /var/www/html/wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters()
#7 /var/www/html/wp-includes/