Ultimate Cron not running because Background process error.

Ever since the upgrade to background process a couple of days ago Ultimate Cron has not been running on most items:

Could not call service uc-queue_views_bulk_operations for callback UltimateCronBackgroundProcessLegacyLauncher::job_callback: stdClass Object
(
    [url] => https://telsoc.org/bgp-start/uc-queue_views_bulk_operations/48597018050a02f5e8e1aaa52f2fb1f2
    [options] => Array
        (
            [method] => POST
            [headers] => Array
                (
                    [User-Agent] => Drupal (+http://drupal.org/)
                    [Accept] => */*
                    [Host] => telsoc.org
                    [Connection] => close
                )

            [data] => 
            [max_redirects] => 3
            [timeout] => 2
            [context] => Resource id #553
            [blocking] => 
            [postpone] => 
        )

    [code] => 0
    [uri] => Array
        (
            [scheme] => https
            [host] => telsoc.org
            [path] => /bgp-start/uc-queue_views_bulk_operations/48597018050a02f5e8e1aaa52f2fb1f2
        )

    [socket] => ssl://telsoc.org:443
    [postponed] => 
    [start] => 1491899169.58
    [data_ready] => 1
    [response] => 
    [error] => Error opening socket ssl://telsoc.org:443
    [end] => 1491899169.59
)

Could not execute background process dispatch for handle uc-queue_views_bulk_operations

In the Configuration settings clicking on the "Determine default service host" button produced the following error message:

Could not determine default service host. Please configure background process in your settings.php