Seaquel
SQL Server error code

SQL Server error 6816

SQL Server raises error 6816 at severity 16, which marks a problem with the query or data that you can correct.

In the FOR XML EXPLICIT clause, ID, IDREF, IDREFS, NMTOKEN, and NMTOKENS attributes cannot be generated as CDATA, XML, or XMLTEXT in '%.*ls'.
Msg6816
Severity16
Group6000–6999

Source: Database Engine events and errors