Seaquel
SQL Server error code

SQL Server error 6831

SQL Server raises error 6831 at severity 16, which marks a problem with the query or data that you can correct.

FOR XML AUTO requires primary keys to create references for '%.*ls'. Select primary keys, or use BINARY BASE64 to obtain binary data in encoded form if no primary keys exist.
Msg6831
Severity16
Group6000–6999

Source: Database Engine events and errors