This error may be seen due to a combination of factors.
RHDCCODE is a user customizable module which defines, among other things, which EBCDIC characters are displayable in ADS maps.
EBCDIC character codes defined with TYPE=HEX in RHDCCODE are not displayable.
If a field on a map has the Automatic Editing attribute enabled, then at runtime, if a non-displayable character is entered into that field, the ADS mapping system will identify that field as being in error and will display the ERROR AT <row>, <column> message if no other error message is defined for the field.
Note that there are several editing attributes that can be set which will enable Automatic Editing, even if the "Automatically edited" flag is not specifically set by the user.
These attributes are documented at Enabling Automatic Editing and Error Handling