title: What could be causing this Chrome security warning with a custom/external protocol?
body: <p>I'm trying to diagnose a co-worker's issue where they are getting a security warning in Chrome when they try to open a URL with a particular custom protocol. They are seeing this warning:</p>
  <p><a href="https://i.stack.imgur.com/YzpOO.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/YzpOO.png" alt="enter image description here" /></a></p>
  <p>I initially thought maybe it was because of the double forward slash being interpreted as HTTPs / telling the browser to use the same protocol, but apparently when that is removed it gets added back in when they submit the request.</p>
  <p>What could be causing this warning? Could it be an issue with how we've registered the custom protocol?</p>