Error when creating/changing/adding to post.

When I create a post, want to change it or add a block to it I get an error page. It has three blocks, attempt recovery, copy the post content or copy the error. When I press attempt recovery, nothing. But this is what I get when I copy the error:

TypeError: this.activateMode is not a function
    at https://c0.wp.com/c/5.1/wp-includes/js/media-views.min.js:1:24791
    at Gt (https://load.sumo.com/9.7affa1e175f5bb16a42a.js:9:5219)
    at Function.Zo (https://load.sumo.com/9.7affa1e175f5bb16a42a.js:9:40178)
    at N.d._createModes (https://c0.wp.com/c/5.1/wp-includes/js/media-views.min.js:1:24751)
    at N.d.initialize (https://c0.wp.com/c/5.1/wp-includes/js/media-views.min.js:1:24160)
    at N.d.initialize (https://c0.wp.com/c/5.1/wp-includes/js/media-views.min.js:1:25798)
    at N.d.initialize (https://c0.wp.com/c/5.1/wp-includes/js/media-views.min.js:1:28670)
    at N.d.b.View (https://c0.wp.com/c/5.1/wp-includes/js/backbone.min.js:1:14137)
    at N.d.constructor (https://c0.wp.com/c/5.1/wp-includes/js/wp-backbone.min.js:1:2616)
    at N.d.constructor (https://c0.wp.com/c/5.1/wp-includes/js/media-views.min.js:1:23607)

HELP!

• This topic was modified 5 years, 12 months ago by Jan Dembowski.
• This topic was modified 5 years, 12 months ago by Jan Dembowski. Reason: Fixed formatting

The page I need help with: [log in to see the link]