can't update social links in advanced options of gallery theme

When I hit "save all options" at the bottom of the page in which I enter the URLs for my social media buttons (Gallery Theme -> Advanced Options), I get sent to an error page with the message below:

Sorry, we can't find the content you're looking for at this URL. Please try selecting a menu item from above or to the side of this message to get where you'd like to go.

Strangely, the only time this isn't happening is when I ONLY enter the twitter URL.

Any help?