Why do I keep getting this error "body cannot be empty" when trying to redirect a page on Tumblr?

I’ve redirected thousands of pages before. I don’t get why it’s not working this time with this new blog I started.

I want to create a page by redirecting specific tags to that page. So for example, my articles about my travels. I tagged them as “travel”, so I have it set so that anything tagged with travel will redirect to its own page titled “My Travels.”

I’ve done this thousands of times before on my other tumblr blogs without any issue.

Now every time I click “Save” this pop-up appears saying “Body cannot be empty”

Excuse my French but what the fuck are they talking about? It’s aggravating me to no end.