Thank you again.

Robert, i will wait.

Many thanks.

This is a specific issue, you should execute the SQLs for all your sites. The update doesn't have this fix. It only fix the first general issue. This two SQLs fix all problems at once.

Many thanks.

First remove the last index, by executing this SQL, make sure the table prefix wp_ is correct:

ALTER TABLE `wp_wpforo_subscribes` DROP INDEX `itemid_type_user_name_user_email`;

Then create the correct one:

ALTER TABLE `wp_wpforo_subscribes` ADD UNIQUE( `itemid`, `type`, `userid`, `user_email`);

Please do nothing, you'll not get any error. The key will be added in future updates. You have nothing to do.

Well Robert it is not ok after all ?  Now I get errors when i try to subscribe to any topic.

 Is that related ?

WordPress database error Duplicate entry '31-topic--' for key 'itemid_type_user_name_user_email' for query INSERT INTO `wp_wpforo_subscribes` (`itemid`, `type`, `confirmkey`, `userid`, `active`, `user_name`, `user_email`) VALUES (31, 'topic', 'c571019dbe7af978f19287b8cffb8526', 2, 1, '', '') made by require('wp-blog-header.php'), require_once('wp-load.php'), require_once('wp-config.php'), require_once('wp-settings.php'), do_action('wp_loaded'), WP_Hook->do_action, WP_Hook->apply_filters, wpforo_actions, wpForoPost->add, do_action('wpforo_after_add_post'), WP_Hook->do_action, WP_Hook->apply_filters, wpforo_topic_auto_subscribe, wpForoSubscribe->add

&

WordPress database error Duplicate entry '31-topic--' for key 'itemid_type_user_name_user_email' for query INSERT INTO `wp_wpforo_subscribes` (`itemid`, `type`, `confirmkey`, `userid`, `active`, `user_name`, `user_email`) VALUES (31, 'topic', '3862037f461d3c6403d1b4bc8ada01b0', 2, 1, '', '') made by do_action('wp_ajax_wpforo_subscribe_ajax'), WP_Hook->do_action, WP_Hook->apply_filters, wpf_subscribe, wpForoSubscribe->add

Just execute this SQl for other websites, there is no issue with that.

I did that last night and they all suffered from the same problem. And because of larger ammount of posts and topics, i spend almost an hour clearing them out.

Not sure if while doing that (all what you proposed above) solved the problem but also deleted some subsriptions from users.