Snapshot and wpsmush errors after upgrading to WP 4.7

Attempting to simply display the login page produced a number of Snapshot referenced errors after upgrading to WP 4.7. One admin was able to login (he also got the errors) and managed to disable Snapshot. Then WPSmush referenced errors displayed. He disabled WP-Smush and now we see no more errors. Here's what these errors looked like:
Notice: Indirect modification of overloaded element of WP_Hook has no effect in /home/wptestingdomain/public_html/wp-content/plugins/snapshot/lib/WPMUDEV/Dashboard/wpmudev-dash-notification.php on line 58

Warning: Cannot modify header information - headers already sent by (output started at /home/wptestingdomain/public_html/wp-content/plugins/snapshot/lib/WPMUDEV/Dashboard/wpmudev-dash-notification.php:58) in /home/wptestingdomain/public_html/wp-includes/pluggable.php on line 1179

Notice: Indirect modification of overloaded element of WP_Hook has no effect in /home/wptestingdomain/public_html/wp-content/plugins/wp-smush-pro/extras/dash-notice/wpmudev-dash-notification.php on line 58

Warning: Cannot modify header information - headers already sent by (output started at /home/wptestingdomain/public_html/wp-content/plugins/wp-smush-pro/extras/dash-notice/wpmudev-dash-notification.php:58) in /home/wptestingdomain/public_html/wp-includes/option.php on line 828

Warning: Cannot modify header information - headers already sent by (output started at /home/wptestingdomain/public_html/wp-content/plugins/wp-smush-pro/extras/dash-notice/wpmudev-dash-notification.php:58) in /home/wptestingdomain/public_html/wp-includes/option.php on line 829