Warning: foreach() argument must be of type array|object, string given in _update_cron_notify()

Facing the same issue on Drupal 9.5.10, PHP 8.1.16 and Ultimate Cron Version: 8.x-2.0-alpha6

I had a similar error on one of my sites.
The error disappear after I updated the my site with the latest version of the module "simple sitemap".

@Londova: Thank for the hint you've given in #6. I already had the latest version of simple_sitemap running and even the latest dev version doesn't solve the issue for me.

To narrow down the error further, I have manually triggered the jobs listed under /admin/config/system/cron/jobs one after the other. The error occurs with the cronjob, which is named in the table with "Update indexes" (Update Manager).

I have strong evidence this is related to an issue belonging to symfony_mailer: " Update emails not working 🐛 Update emails not working Fixed "

After applying the patch, I did not get any more error messages on cron run.

Do you mean it's related to changes by 🐛 Update emails not working Fixed ?
which was fixed this week in 🐛 Circular reference detected for service symfony mailer config override in multilingual sites Fixed
Maybe adding a basic check of is_array before the loop will not have this again by any other modules.

@Rajab: Thanks for your feedback. In my case, the error described in this issue did not go away by applying the patch from 🐛 Circular reference detected for service symfony mailer config override in multilingual sites Fixed . I had to apply the patch from 🐛 Update emails not working Fixed

But it would be good if other people could review this, as I can't rule out other factors for sure.