XF 2.2 Error on adding a Moderator

[Shawn Gossman]

Getting an error when adding a Moderator via Admin Panel:

Oops! We ran into some problems.
Oops! We ran into some problems. Please try again later. More error details may be in the browser console.

Upon checking Browser Console, I get the following:

Failed to load resource: the server responded with a status of 404 ()

I cannot add the rest because it's over the forum's character count limit. But coming from: "core-compiled.js?_v=4da8d839" page.

Any ideas of what this problem can be?