Fix wordpress error & issue

Since upgrading Wordpress to 5.0+ I get the following error each time I edit ANY page: "Failed to load plugin url: [login to view URL]" Also, my lazy load boxes plugin breaks each time I edit the page. The site and the lazy load boxes work as is on live site, but when I try to edit using Wordpress editor, from both visual and code view, the lazy load boxes fail to render and the result is just code on the page, so I cannot publish any chnages to anything on a page with the Lazy load boxes or it breaks. My home page is where this plugin is today. If you go to HTTP://[login to view URL], the lazy load boxes are (Plan, Manage, Secure). I'm trying to change the & in the first box to 'and' but it breaks the page by not rendering lazy load boxes as explained above. I really need to make changes to my home page, and this was not an issue before upgrade. I do wish to keep the updated version of WordPress.