Seaquel
SQL Server error code

SQL Server error 6309

SQL Server raises error 6309 at severity 16, which marks a problem with the query or data that you can correct.

XML well-formedness check: the data for node '%.*ls' contains a character (0x%04X) which is not allowed in XML.
Msg6309
Severity16
Group6000–6999

Source: Database Engine events and errors