URLs containing characters that are not allowed in the server name, such as exclamation marks, parentheses, and so on, are blocked for security reasons. Instead of the URL, an "opera:illegal-url" text is shown in the URL field, and an error page with a brief explanation appears.
Opera does this to prevent phishing attacks.
Note: Opera's list of illegal characters is slightly longer than the official IDNA list.
Need help? Hit F1 anytime while using Opera to access our online help files, or go here.