Editorial illustration.
Originally published 16 June 2023; rewritten and reviewed on 15 October 2026.
After upgrading a project from Kentico 8.2 to Kentico 12, the site initially looked healthy. The problem appeared when I added a column to a BizForm and tried to save the field. The exception said that SQL type datetime was not registered and referred to RegisterDataTypes.
That sequence changed what I considered an adequate upgrade check. Browsing existing content had not exercised the administrative operation that needed to interpret and update the form’s database definition.
Follow the operation that failed
The stack trace passed through field-definition and table-structure code. In this project, the original investigation led to FormInserted and FormUpdated columns still using the older SQL datetime type.
The archived fix changed those columns to datetime2, handling their default constraints around the change. That describes this particular diagnosis. It is not evidence that every exception with the same wording has the same cause.
Rehearse the schema change before production
Back up the database and verify that it can be restored. Reproduce the failure on a representative upgraded copy, inspect the actual column and constraint definitions and check the expected schema for that Kentico version.
A change script must use the real table and constraint names, preserve the intended defaults and nullability, and account for dependencies. I would review it with the database owner and use supported upgrade guidance before applying it. A generic ALTER TABLE pasted from a blog is not a substitute for that inspection.
Extend the upgrade acceptance test
After the correction, the important verification is the operation that originally failed: editing and saving the form definition. Check existing submissions, creating a new submission and other affected form operations as well.
The lesson from this project is that administrative writes belong in upgrade testing. A site that displays its old content successfully can still have a schema problem waiting for the next editor.