Seaquel
SQL Server error code

SQL Server error 2509

SQL Server raises error 2509 at severity 16, which marks a problem with the query or data that you can correct.

DBCC CHECKCONSTRAINTS failed due to an internal query error. Please run DBCC CHECKDATABASE to ensure your data consistency.
Msg2509
Severity16
Group2000–2999

Source: Database Engine events and errors