Seaquel
SQL Server error code

SQL Server error 9503

SQL Server raises error 9503 at severity 16, which marks a problem with the query or data that you can correct.

Errors and/or warnings occurred when processing the XQuery statement for XML data type method '%.*ls'. See previous error messages for more details.
Msg9503
Severity16
Group9000–9999

Source: Database Engine events and errors