After upgrading to version 9, you cannot save or publish content with special characters such as '&' or '/' in the content title.
Starting with version 9.0, Ektron now enforces special characters. Prior to this version, we did not enforce this policy even though special characters have been known to cause issues. We changed that policy in version 9 to better fit with standards around the internet.
From our documentation:
Title — Enter a title for the content. It cannot include these characters: \ / * > < | &
These characters were unsupported in older versions, it is just being enforced in 9.0.
Your user will need to make a change to the title in order not to see this error.