Error: “Updating Failed”

I have a newish site: https://ownthebackyard.com/ and every time that I make a change to my home page and “update” I get a dark pink stripe across the top of my page “Updating Failed”. When I look at my page after “saving”, the changes that I made, they are fine and the updates have been saved.
I went into my posts and tested if this would happen with those posts (on a few) but it did not flash the message up on the top of my post.
Do you have any idea why this is happening?
Why only on my home page?
Thanks for your help.
Regards,
Janek

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