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SchedulerOptionsCustomization.AllowAppointmentConflicts Property

Gets or sets whether a user is allowed to share the schedule time between two or more appointments.

Namespace: DevExpress.XtraScheduler

Assembly: DevExpress.XtraScheduler.v22.2.Core.Desktop.dll

NuGet Package: DevExpress.Scheduler.CoreDesktop


public AppointmentConflictsMode AllowAppointmentConflicts { get; set; }

Property Value

Type Default Description
AppointmentConflictsMode Allowed

An AppointmentConflictsMode enumeration value specifying whether the time interval of two or more appointments can intersect or not, if these appointments belong to the same resource(s).

Available values:

Name Description

Appointments conflicts are allowed. This means that appointment intervals can intersect for the same resource (or for at least for one of the resources to which they belong, if resources are shared).


Appointments conflicts are forbidden. This means that appointment intervals can’t intersect each other for the same resource (or for at least for one of the resources to which they belong, if resources are shared).


Whether the conflicts are resolved or not is determined manually in the corresponding event handler.

Property Paths

You can access this nested property as listed below:

Library Object Type Path to AllowAppointmentConflicts
WinForms Controls SchedulerControl
ASP.NET Bootstrap Controls BootstrapScheduler
eXpressApp Framework ASPxSchedulerListEditor
ASP.NET MVC Extensions MVCxScheduler
ASP.NET Web Forms Controls ASPxScheduler


By default, end users can share the schedule time between two or more appointments. Use the AllowAppointmentConflicts property to control the availability of such functionality to end-users.

If this property is set to AppointmentConflictsMode.Allowed, the time interval of two or more appointments can intersect and sharing the schedule time between the appointments is allowed. Set the AllowAppointmentConflicts property to AppointmentConflictsMode.Forbidden to prevent scheduling (or rescheduling) of two or more appointments for the same time.


If the AllowAppointmentConflicts property is set to AppointmentConflictsMode.Custom, then whether an end-user is allowed to share the schedule time between two or more appointments or not is decided in the SchedulerControl.AllowAppointmentConflicts event handler.

Change the Conflict Message

When a conflict occurs, the Scheduler shows a message box that notifies users about this conflict. The code below illustrates how to change this message box text.

public Form1() {
    SchedulerResLocalizer.Active = new CustomSchedulerResLocalizer();

public class CustomSchedulerResLocalizer : SchedulerResLocalizer {
    public override string GetLocalizedString(SchedulerStringId id) {
        if(id == SchedulerStringId.Msg_Conflict)
            return "_YOUR_CUSTOM_MESSAGE_TEXT_";
            return base.GetLocalizedString(id);


This example handles the SchedulerControl.AllowAppointmentConflicts event to prevent movement of an appointment to a range where another appointment exists. The SchedulerOptionsCustomization.AllowAppointmentConflicts property is set to AppointmentConflictsMode.Custom to process appointment conflicts in a custom manner.

The code in the SchedulerControl.AllowAppointmentConflicts event handler checks whether the time interval of the modified appointment intersects with other appointments, including recurrent series and exceptions. If such an appointment is found, it is added to the AppointmentConflictEventArgs.Conflicts collection. If the collection has at least one element, a conflict occurs and the Scheduler cancels changes.

To paint conflicts, the example handles the SchedulerControl.CustomDrawAppointmentBackground event. The AppointmentConflictsCalculator.CalculateConflicts method is called in this event handler to get the current conflicts.

View Example

schedulerControl1.OptionsCustomization.AllowAppointmentConflicts = AppointmentConflictsMode.Custom;
private void SchedulerControl1_AllowAppointmentConflicts(object sender, AppointmentConflictEventArgs e) {
    FillConflictedAppointmentsCollection(e.Conflicts, e.Interval, ((SchedulerControl)sender).DataStorage.Appointments.Items, e.AppointmentClone);

void FillConflictedAppointmentsCollection(AppointmentBaseCollection conflicts, TimeInterval interval,
    AppointmentBaseCollection collection, Appointment currApt) {
    for(int i = 0; i < collection.Count; i++) {
        Appointment apt = collection[i];
        if(new TimeInterval(apt.Start, apt.End).IntersectsWith(interval) & !(apt.Start == interval.End || apt.End == interval.Start)) {
            if(apt.ResourceId == currApt.ResourceId) {
        if(apt.Type == AppointmentType.Pattern) {
            FillConflictedAppointmentsCollection(conflicts, interval, apt.GetExceptions(), currApt);

The following code snippets (auto-collected from DevExpress Examples) contain references to the AllowAppointmentConflicts property.


The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

See Also