Error Message: "The page at [site url] says: 1"

Thanks to everyone who contributes to this forum – it is an invaluable resource for newbies like me!

I just started utilizing “parent and children” pages, and installed the plugin “PagesTo” so that I could have a page in the navigation bar that does not link to anything, with the sole purpose of having that page serve as a parent (and so that the children show up when the parent page name is moused over in the nav bar). Now, whenever any page on my site is loaded, I get the error message “The page at https://vengaviral.com says: 1”. If I click OK, the page loads.

Any idea what this is? Thanks in advance!