Symptoms
When running the "Update to 9.0" upgrade script, I see a series of errors in SQL Server Management Studio like 'Dropping constraints from [dbo].[RatingCommentHelpfulness]', 'Creating [dbo].[aspdnsf_CreateIndexes]', etc.
Cause
These are not actually errors, the new upgrade script simply outputs more information about what it's doing that previous versions did. This is for troubleshooting purposes should any issues arise with the script.
Solution
As long as no actual errors are encountered (red text with error details), these messages can be ignored.