Here is a simple solution of this problem that worked at my side in the code behind:
sender, AppointmentUpdateEventArgs e)
String csname1 =
Type cstype =
// Get a ClientScriptManager reference from the Page class.
ClientScriptManager cs = Page.ClientScript;
// Check to see if the startup script is already registered.
(e.ModifiedAppointment.End.TimeOfDay.TotalMinutes > 1439)
String cstext1 =
"alert('The End time should not be later than 23:59!');"
cs.RegisterStartupScript(cstype, csname1, cstext1,
Hope this will help you.
the Telerik team
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