RadScheduler: Error received when trying to save modified appointment "Update requires a valid UpdateCommand when passed DataRow collection with modified rows."

Hello, Dominic,

According to the provided information, it seems to be more related to the database than to the RadScheduler control. I have researched in general programming forums and found the following useful threads:
https://stackoverflow.com/questions/588361/update-requires-a-valid-updatecommand-when-passed-datarow-collection-with-modifi 
https://social.msdn.microsoft.com/Forums/en-US/666835a2-50ec-415f-ba30-bb80ca51c91b/update-requires-a-valid-updatecommand-when-passed-datarow-collection-with-modified-rows?forum=adodotnetdataproviders 
https://www.codeproject.com/Questions/783318/Update-requires-a-valid-UpdateCommand-when-passed 

I would recommend you to have a look at the following step-by-step tutorial which demonstrates how to setup and bind RadScheduler:
https://docs.telerik.com/devtools/winforms/knowledge-base/scheduler-databinding-tutorial 

A complete solution providing a C# and VB.NET project is also available for your reference at the end of the article. Please give it a try and see how it works on your end. 

I hope this information helps. If you need any further assistance please don't hesitate to contact me. 

Regards,
Dess | Tech Support Engineer, Principal
Progress Telerik