You need do upgrade database to the HotFix 6.0.23.

•Run Kentico Hotfix Utility (Hotfix.exe) from the location where you installed it.

•Select your project installation folder using the Browse button or type in the path to the project manually.

•Use the application to back up your project files and/or database in case you haven’t already done so.

•Select whether you want to update files, database or both. It is recommended to update both the project files and the database.

•Choose a method of taking the project offline and back online.

•Click Next to start the update procedure.

After the update finishes, click Next to view any problems that may have occurred and the instructions to solve them.