The transfer attempted appeared to contain a data leak?

Question

Getting this error message in the browser:

Attention!!!

The transfer attempted appeared to contain a data leak!

URL=http://test-login.becreview.com/domain/User_Edit.aspx?UserID=b5d77644-b10e-44e0-a007-3b9a5e0f4fff

I've seen this before but I'm not sure what causes it. It doesn't look like a browser error or an asp.net error. Could it be some sort of proxy error? What causes it?

That domain is internal so you won't be able to go to it. Also the page has almost no styling. An h1 for "Attention!!!" and the other two lines are wrapped in p tags if that helps any.

Answer 1

For anyone else investigating this message, it appears to be a Fortinet firewall's default network data-leak prevention message.