Black Bar on top of WP website

Looking for help. Not sure what happened but updated a post and now there is a “black bar” on the top of our website. Also pushed the dashboard in WP down with warning messages about “wp-content\plugins\wp-super-cache\wp-cache.php.” Has anyone else encountered this and know how to solve? The website is https://www.thecomedybook.com to view what is going on at the top of all pages. Thanks in advance for any help.

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