Scenario
When creating or editing content pages in RiSE/WCM website it is common to add hyperlinks. After adding links to a page's Content HTML iPart and clicking "OK", occasionally an error will occur indicating that there are "Illegal characters in path."
Cause of the Error Message
This error occurs when a hyperlink is added which contains special characters. Usually the special character causing the error is an ampersand (&), however others may also be the culprit.
Reason the Message is Displayed
Some webpages provide functionality which makes use of URL parameters. These URL parameters require special characters to be included in the link so that the page features will work properly. In the case of malicious webpages, URL parameters also have the potential to manipulate data and can therefore pose a security risk. The Content HTML iPart displays this message in order to protect the end user. Generally, the message should be considered a warning rather than an error.
Solution
If the link being created goes to a known-safe location then this error can safely be ignored as those special characters are often times necessary for the link to work properly. If the message is displayed after clicking "OK" for the Content HTML iPart, simply click "OK" a second time to bypass the message and proceed. The link will remain intact.
If the link points to a questionable location then it is recommended to remove the link, or remove the URL parameters (everything including, and after the question mark).