Troubleshooting problems with DBCC commands in SQL Server 2017 If you have problems with SQL Server 2017 DBCC commands, review this troubleshooting checklist to find potential solutions. 1. The error 2509 occurs when you run DBCC CHECKCONSTRAINTS command. This is the error message text: “DBCC CHECKCONSTRAINTS failed due to an internal query error”. To work around this problem, you can...