Why am I seeing an "Invalid XML character" error when importing a topic?

Some XML characters are invalid and cannot be imported into IXIASOFT CCMS.


I get an "Invalid XML character" error when trying to import a topic that has the following text:
When you open a note that has special Unicode characters (such as  or ) in the note accumulator, an error is displayed.  


Escape or remove the character from topic prior to importing it into the IXIASOFT CCMS.