Seaquel
SQL Server error code

SQL Server error 3809

SQL Server raises error 3809 at severity 16, which marks a problem with the query or data that you can correct.

Upgrade of database "%.*ls" failed because index "%.*ls" on object ID %d has the same name as that of another index on the same table.
Msg3809
Severity16
Group3000–3999

Source: Database Engine events and errors