diff --git a/BeWoPlanerMobil/Controllers/CustomerController.cs b/BeWoPlanerMobil/Controllers/CustomerController.cs
index 07f60b221..8066b5d75 100644
--- a/BeWoPlanerMobil/Controllers/CustomerController.cs
+++ b/BeWoPlanerMobil/Controllers/CustomerController.cs
@@ -1,10 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Globalization;
-using System.IO;
-using System.Linq;
-using System.Web.Mvc;
-using BeWo.Report.DefaultReports;
+using BeWo.Report.DefaultReports;
 using BeWo.View.Navigation.Filter;
 using BeWoPlanerMobil.Models;
 using BeWoPlanerMobil.Service;
@@ -15,6 +9,13 @@ using BS.Shared.DataContracts;
 using BS.Shared.DataContracts.Compact;
 using BS.Shared.Extensions;
 using DevExpress.XtraReports.UI;
+using Newtonsoft.Json;
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.IO;
+using System.Linq;
+using System.Web.Mvc;
 
 namespace BeWoPlanerMobil.Controllers
 {
@@ -1409,6 +1410,46 @@ namespace BeWoPlanerMobil.Controllers
         {
             return SaveCollapsibleStatusToModel(Model, isOpen, identifier);
         }
+
+        [Authorize]
+        public string CheckForOverlappingAbsenceTimes(string startStr, string endStr, long oid)
+        {
+            if(false == DateTime.TryParse(startStr, out var start))
+            {
+                start = DateTime.MinValue;
+            }
+
+            if(false == DateTime.TryParse(endStr, out var end))
+            {
+                end = DateTime.MaxValue;
+            }
+
+            var messages = new List<string>();
+
+            var hasOverlappingAbsenceTimes = false;
+
+            foreach(var absenceTime in Model.SelectedCustomer.AbsenceTimes)
+            {
+                var alpha = absenceTime.Start ?? DateTime.MinValue;
+                var omega = absenceTime.End ?? DateTime.MaxValue;
+
+                if(start >= alpha && start <= omega ||
+                   alpha >= start && alpha <= end ||
+                   end >= alpha && end <= omega ||
+                   omega >= start && omega <= end)
+                {
+                    hasOverlappingAbsenceTimes = true;
+                    break;
+                }
+            }
+
+            if(hasOverlappingAbsenceTimes)
+            {
+                messages.Add("Die Abwesenheit überschneidet sich mit mindestens einer bereits vorhandenen Abwesenheit.<br/><br/>Möchten Sie trotzdem fortfahren?");
+            }
+
+            return JsonConvert.SerializeObject(messages);
+        }
     }
 
     public enum CustomerReportType
diff --git a/BeWoPlanerMobil/Controllers/DevExpressSchedulerController.cs b/BeWoPlanerMobil/Controllers/DevExpressSchedulerController.cs
index 5d024e086..2b2c6bed8 100644
--- a/BeWoPlanerMobil/Controllers/DevExpressSchedulerController.cs
+++ b/BeWoPlanerMobil/Controllers/DevExpressSchedulerController.cs
@@ -339,6 +339,19 @@ namespace BeWoPlanerMobil.Controllers
             return PartialView("SchedulerPagePartial", Model);
         }
 
+        [Authorize]
+        public string GetAppointmentType(long oid)
+        {
+            var appointment = Model.GetAppointmentByOid(oid);
+
+            var showMenuItem = false;
+
+            //var isTask = appointment.IsTask;
+            //var isAbsenceTime = appointment.
+
+            return JsonConvert.SerializeObject(showMenuItem);
+        }
+
         [Authorize]
         public ActionResult CheckEmployeeAvailability(string startString, string endString)
         {
diff --git a/BeWoPlanerMobil/Controllers/EmployeeController.cs b/BeWoPlanerMobil/Controllers/EmployeeController.cs
index 1b9e5f0ec..6313b2734 100644
--- a/BeWoPlanerMobil/Controllers/EmployeeController.cs
+++ b/BeWoPlanerMobil/Controllers/EmployeeController.cs
@@ -1,12 +1,14 @@
 using System;
-using System.Diagnostics;
+using System.Collections.Generic;
 using System.Linq;
 using System.Web.Mvc;
 using BeWoPlanerMobil.Models;
 using BeWoPlanerMobil.Service;
 using BeWoPlanerMobil.Util;
+using Bogus.DataSets;
 using BS.Shared;
 using BS.Shared.DataContracts;
+using Newtonsoft.Json;
 
 namespace BeWoPlanerMobil.Controllers
 {
@@ -276,5 +278,59 @@ namespace BeWoPlanerMobil.Controllers
 
             return PartialView("AbsenceTimePartial", Model);
         }
+
+        [Authorize]
+        public string CheckForOverlappingAbsenceTimes(string startStr, string endStr, long oid)
+        {
+            var hasNoEnd = false;
+
+            if(false == DateTime.TryParse(startStr, out var start))
+            {
+                start = DateTime.MinValue;
+            }
+
+            if(false == DateTime.TryParse(endStr, out var end))
+            {
+                hasNoEnd = true;
+
+                end = DateTime.MaxValue;
+            }
+
+            var messages = new List<string>();
+
+            var hasOverlappingAbsenceTimes = false;
+
+            foreach(var absenceTime in Model.SelectedEmployee.AbsenceTimes)
+            {
+                var alpha = absenceTime.Start ?? DateTime.MinValue;
+                var omega = absenceTime.End ?? DateTime.MaxValue;
+
+                if(start >= alpha && start <= omega ||
+                   alpha >= start && alpha <= end ||
+                   end >= alpha && end <= omega ||
+                   omega >= start && omega <= end)
+                {
+                    hasOverlappingAbsenceTimes = true;
+                    break;
+                }
+            }
+
+            if(hasOverlappingAbsenceTimes)
+            {
+                messages.Add($"Die Abwesenheit überschneidet sich mit mindestens einer bereits vorhandenen Abwesenheit.{(hasNoEnd ? "<br/><br/>" : "<br/>")}");
+            }
+
+            if(hasNoEnd)
+            {
+                messages.Add("Die Abwesenheit hat kein Enddatum.<br/>Beachten Sie, dass Abwesenheiten ohne Enddatum unbegrenzt weiterlaufen und es dadurch zu Fehlberechnungen im Stunden- und Urlaubskonto kommen kann.");
+            }
+
+            if(messages.Any())
+            {
+                messages.Add("<br/><br/>Möchten Sie trotzdem fortfahren?<br/>");
+            }
+
+            return JsonConvert.SerializeObject(messages);
+        }
     }
 }
\ No newline at end of file
diff --git a/BeWoPlanerMobil/Controllers/IAbsenceTimeController.cs b/BeWoPlanerMobil/Controllers/IAbsenceTimeController.cs
index 231451d84..0d82c79d9 100644
--- a/BeWoPlanerMobil/Controllers/IAbsenceTimeController.cs
+++ b/BeWoPlanerMobil/Controllers/IAbsenceTimeController.cs
@@ -23,5 +23,8 @@ namespace BeWoPlanerMobil.Controllers
 
         [Authorize]
         ActionResult DeleteAbsenceTime(long absenceTimeOid);
+
+        [Authorize]
+        string CheckForOverlappingAbsenceTimes(string startStr, string endStr, long oid);
     }
 }
diff --git a/BeWoPlanerMobil/Controllers/MainController.cs b/BeWoPlanerMobil/Controllers/MainController.cs
index 8d2386b2c..7c42446ea 100644
--- a/BeWoPlanerMobil/Controllers/MainController.cs
+++ b/BeWoPlanerMobil/Controllers/MainController.cs
@@ -4250,7 +4250,10 @@ namespace BeWoPlanerMobil.Controllers
 
             Model.TransferringAppointmentOid = TempData[TempDataConstants.AppointmentOidKey] as long?;
 
-            var isSerientermin = TempData[TempDataConstants.AppointmentIsSerienterminKey] is true;
+            var recurrenceIndex = (int?) TempData[TempDataConstants.AppointmentRecurrenceIndexKey];
+
+            var isSerientermin = recurrenceIndex.HasValue;
+            //TempData[TempDataConstants.AppointmentIsSerienterminKey] is true;
 
             if((false == Model.TransferringAppointmentOid.HasValue && false == isSerientermin) || false == Model.LoggedInEmployee.EmployeeOid.HasValue)
             {
@@ -4437,7 +4440,9 @@ namespace BeWoPlanerMobil.Controllers
                 var pattern = StaticAppointmentFactory.CreateAppointment(AppointmentType.Pattern);
                 pattern.RecurrenceInfo.FromXml(recurrenceInfo);
 
-                var apt = pattern.CreateException(AppointmentType.ChangedOccurrence, appointment.RecurrenceIndex);
+                var apt = pattern.CreateException(AppointmentType.ChangedOccurrence, recurrenceIndex.Value);
+
+                var changedOccurrence = SchedulerAppointmentDC.RecurringExceptionFromDevExpressAppointment(apt, appointment);
 
                 var x = apt.RecurrenceIndex;
             }
diff --git a/BeWoPlanerMobil/Controllers/SchedulerController.cs b/BeWoPlanerMobil/Controllers/SchedulerController.cs
index 844fff7f9..2a3b710ff 100644
--- a/BeWoPlanerMobil/Controllers/SchedulerController.cs
+++ b/BeWoPlanerMobil/Controllers/SchedulerController.cs
@@ -1431,6 +1431,11 @@ namespace BeWoPlanerMobil.Controllers
 
             TempData[TempDataConstants.AppointmentOidKey] = appointment?.SchedulerAppointmentOid;
 
+            if(appointment?.RecurrenceInfo != null)
+            {
+                TempData[TempDataConstants.AppointmentRecurrenceIndexKey] = appointment?.RecurrenceIndex;
+            }
+
             TempData[TempDataConstants.AppointmentStartKey] = appointment?.StartDate;
             TempData[TempDataConstants.AppointmentEndKey] = appointment?.EndDate;
             TempData[TempDataConstants.AppointmentSubjectKey] = appointment?.Subject;
diff --git a/BeWoPlanerMobil/Models/CustomerModel.cs b/BeWoPlanerMobil/Models/CustomerModel.cs
index 1bb2b35c4..b9683e832 100644
--- a/BeWoPlanerMobil/Models/CustomerModel.cs
+++ b/BeWoPlanerMobil/Models/CustomerModel.cs
@@ -16,6 +16,7 @@ namespace BeWoPlanerMobil.Models
         public long? ObjectOid => SelectedCustomerOid;
         public TableID ObjectTid => TableID.Customer;
         public string HtmlPrefix => "customer";
+        public long? AbsenteeOid => SelectedCustomerOid;
 
         public IAbsenceTime AbsenceTimeObject
         {
diff --git a/BeWoPlanerMobil/Models/EmployeeModel.cs b/BeWoPlanerMobil/Models/EmployeeModel.cs
index f7563e13c..9bb3547b7 100644
--- a/BeWoPlanerMobil/Models/EmployeeModel.cs
+++ b/BeWoPlanerMobil/Models/EmployeeModel.cs
@@ -28,6 +28,7 @@ namespace BeWoPlanerMobil.Models
             set => EmployeeSessionModel.SelectedAbsenceTimeObjectOid = value;
         }
 
+        public long? AbsenteeOid => SelectedEmployeeOid;
         public EmployeeModel()
         {
             SessionModel = new EmployeeSessionModel();
diff --git a/BeWoPlanerMobil/Models/IAbsenceTimeModel.cs b/BeWoPlanerMobil/Models/IAbsenceTimeModel.cs
index 19ed5f6ea..ef1969be4 100644
--- a/BeWoPlanerMobil/Models/IAbsenceTimeModel.cs
+++ b/BeWoPlanerMobil/Models/IAbsenceTimeModel.cs
@@ -13,5 +13,6 @@ namespace BeWoPlanerMobil.Models
         IAbsenceTime             AbsenceTimeObject        { get; set; }
         Dictionary<string, bool> Collapsibles2IsShown     { get; set; }
         List<SelectListItem>     AbsenceReasonItems       { get; }
+        long?                    AbsenteeOid              { get; }
     }
 }
diff --git a/BeWoPlanerMobil/Scripts/ownSoft-Scripts/mobileUtils.js b/BeWoPlanerMobil/Scripts/ownSoft-Scripts/mobileUtils.js
index f1acec2eb..6d462638c 100644
--- a/BeWoPlanerMobil/Scripts/ownSoft-Scripts/mobileUtils.js
+++ b/BeWoPlanerMobil/Scripts/ownSoft-Scripts/mobileUtils.js
@@ -552,4 +552,48 @@ function getTimeStamp(dateObject, showSeconds, showMilliseconds) {
     } else {
         return `${dd}.${MM}.${yyyy} ${HH}:${mm}`;
     }
-}
\ No newline at end of file
+}
+
+function getUnixTimeStamp(dateObject, showSeconds) {
+    const dd = String(dateObject.getDate()).padStart(2, "0");
+    const MM = String(dateObject.getMonth() + 1).padStart(2, "0");
+    const yyyy = dateObject.getFullYear();
+    const HH = String(dateObject.getHours()).padStart(2, "0");
+    const mm = String(dateObject.getMinutes()).padStart(2, "0");
+    const ss = String(dateObject.getSeconds()).padStart(2, "0");
+    const ms = String(dateObject.getMilliseconds()).padStart(2, "0");
+
+    return showSeconds ? `${yyyy}-${MM}-${dd} ${HH}:${mm}:${ss}` : `${yyyy}-${MM}-${dd} ${HH}:${mm}`;
+}
+
+    function showMessagePopupWithHtmlAndCallbacks(title, messageAsHtml, callback, cancelBtnCallback) {
+        $("#popupTitle").text(title);
+
+        if(messageAsHtml !== null) {
+            $("#modal-body").html("<p id=\"popupMessage\"></p>");
+        }
+
+        $("#popupMessage").html(messageAsHtml);
+
+        $("#message-popup-ok-btn").off("click");
+
+        if(typeof callback === "function") {
+            $("#message-popup-ok-btn").on("click", function() {
+                callback();
+            });
+        }
+
+        if(typeof cancelBtnCallback === "function") {
+            $("#message-popup-close-btn").off("click");
+            $("#message-popup-close-btn").on("click", function() {
+                cancelBtnCallback();
+            });
+        }
+
+        $("#messagePopup").modal(
+            {
+                backdrop: "static",
+                keyboard: false
+            }
+        );
+    }
\ No newline at end of file
diff --git a/BeWoPlanerMobil/Util/MobileUtils.cs b/BeWoPlanerMobil/Util/MobileUtils.cs
index a7bd9e74e..201718bbb 100644
--- a/BeWoPlanerMobil/Util/MobileUtils.cs
+++ b/BeWoPlanerMobil/Util/MobileUtils.cs
@@ -625,5 +625,12 @@ namespace BeWoPlanerMobil.Util
 
             return "5px solid #C0FFD0";
         }
+
+        public static string GetCssRightValue(DevExpress.XtraScheduler.Appointment appointment)
+        {
+            var serviceRecords = appointment.CustomFields[nameof(SchedulerAppointmentDC.ServiceRecordList)] as List<ServiceRecordDC> ?? new List<ServiceRecordDC>();
+
+            return serviceRecords.Any() ? "40px" : "23px";
+        }
     }
 }
\ No newline at end of file
diff --git a/BeWoPlanerMobil/Views/Customer/Customer.cshtml b/BeWoPlanerMobil/Views/Customer/Customer.cshtml
index 5d5e46c7a..c96a8f8bb 100644
--- a/BeWoPlanerMobil/Views/Customer/Customer.cshtml
+++ b/BeWoPlanerMobil/Views/Customer/Customer.cshtml
@@ -1079,7 +1079,7 @@
     }
 </div>
 
-@if(Model.HasRightToViewCustomerAbsenceTimes)
+@if(Model.HasRightToViewCustomerAbsenceTimes && Model.SelectedCustomer != null)
 {
     <div class="modal" tabindex="-1" role="dialog" id="customer-absence-times-form-popup">
         <div class="modal-dialog modal-lg" role="document">
diff --git a/BeWoPlanerMobil/Views/DevExpressScheduler/DevExpressScheduler.cshtml b/BeWoPlanerMobil/Views/DevExpressScheduler/DevExpressScheduler.cshtml
index 1536a5788..8f6fab724 100644
--- a/BeWoPlanerMobil/Views/DevExpressScheduler/DevExpressScheduler.cshtml
+++ b/BeWoPlanerMobil/Views/DevExpressScheduler/DevExpressScheduler.cshtml
@@ -118,6 +118,23 @@
 	        console.error(error);
         }
     }
+
+    function OnAppointmentMenuPopup(s, e) {
+        const selectedAppointment = scheduler.GetAppointmentById(scheduler.GetSelectedAppointmentIds()[0]);
+        console.log(selectedAppointment);
+        for(let i = 0; i < e.item.items.length; i++) {
+	        const currentItem = e.item.items[i];
+
+            if(currentItem.name === "ToServiceRecord") {
+		        const isTask = selectedAppointment.customField("IsTask");
+		        const isAbsenceTime = selectedAppointment.customField("IsAbsenceTime");
+
+                if(isTask === true || isAbsenceTime === true) {
+	                currentItem.SetVisible(false);
+                }
+	        }
+        } 
+    }
 </script>
 
 @using(Html.BeginForm())
diff --git a/BeWoPlanerMobil/Views/DevExpressScheduler/HorizontalAppointmentTemplatePartial.cshtml b/BeWoPlanerMobil/Views/DevExpressScheduler/HorizontalAppointmentTemplatePartial.cshtml
index 8b3dad682..f8f6edf8e 100644
--- a/BeWoPlanerMobil/Views/DevExpressScheduler/HorizontalAppointmentTemplatePartial.cshtml
+++ b/BeWoPlanerMobil/Views/DevExpressScheduler/HorizontalAppointmentTemplatePartial.cshtml
@@ -1,4 +1,5 @@
 @using BeWoPlanerMobil.Util
+@using BS.Shared.DataContracts
 @model DevExpress.XtraScheduler.Appointment
 
 @functions
@@ -37,16 +38,45 @@
         margin-right: 0;
     }
 
-    .horizonta.horizontal-appointment-label {
+    .horizontal-appointment-label {
         display: inline-block;
         margin-right: 5px;
+        margin-left: 0.25em;
+        margin-top: 0.25em;
+    }
+
+    .horizontal-recurring-label-span {
+        margin-top: 5px;
+        margin-right: 10px;
+        right: 10px;
     }
 </style>
 
     <div class="horizontal-appointment-template-div" style="border-left: @MobileUtils.GetLeftAppointmentBorder(Model);background: @MobileUtils.GetAppointmentRightBackground(Model) right / 5px 100% no-repeat, #C0FFD0;">
         <div class="horizontal-appointment-info">
-            <label class="horizontal-appointment-label">
-	            @GetHeaderTime() <span style="font-weight: bold;">@GetSubjectAndLocation()</span>
-            </label>
+	        <label class="horizontal-appointment-label">
+		        @GetHeaderTime() <span style="font-weight: bold;">@GetSubjectAndLocation()</span>
+	        </label>
+	        <div class="clearfix d-inline">
+		        @if(Model.CustomFields[nameof(SchedulerAppointmentDC.ServiceRecordList)] is List<ServiceRecordDC> serviceRecords && serviceRecords.Any())
+		        {
+			        <i class="fas fa-clock text-bewo-service-records float-right horizontal-recurring-label-span mr-1"></i>
+		        }
+
+		        @if(Model.IsRecurring)
+		        {
+			        if(Model.Id is long)
+			        {
+				        <span class="fa-stack fa-1x text-info float-right" style="height:fit-content;width:fit-content;position:absolute;top:10px;right:@MobileUtils.GetCssRightValue(Model);">
+					        <i class="fas fa-solid fa-stack-1x fa-slash"></i>
+					        <i class="fas fa-solid fa-stack-1x fa-sync-alt"></i>
+				        </span>
+			        }
+			        else
+			        {
+				        <i class="fas fa-sync-alt text-info float-right mr-1 horizontal-recurring-label-span"></i>
+			        }
+		        }
+	        </div>
         </div>
     </div>
\ No newline at end of file
diff --git a/BeWoPlanerMobil/Views/DevExpressScheduler/SchedulerPagePartial.cshtml b/BeWoPlanerMobil/Views/DevExpressScheduler/SchedulerPagePartial.cshtml
index 065251f70..28e6a1867 100644
--- a/BeWoPlanerMobil/Views/DevExpressScheduler/SchedulerPagePartial.cshtml
+++ b/BeWoPlanerMobil/Views/DevExpressScheduler/SchedulerPagePartial.cshtml
@@ -58,6 +58,8 @@
 		    e.Menu.Items.Add(new MenuItem("Verfügbare Mitarbeiter anzeigen", "ShowAvailableEmployees"));
 	    }
 
+	    e.Menu.ClientSideEvents.PopUp = "OnAppointmentMenuPopup";
+
         foreach(MenuItem item in e.Menu.Items)
         {
             if(invisibleMenuItemNames.Contains(item.Name))
@@ -160,6 +162,7 @@
             settings.OptionsToolTips.ShowSelectionToolTip = false;
             settings.ClientSideEvents.ActiveViewChanging = "onActiveViewChanged";
             settings.ClientSideEvents.MenuItemClicked = "onMenuItemClicked";
+            
             settings.PopupMenuShowing = PopupMenuShowing;
 
             settings.Storage.Appointments.Assign(SchedulerHelper.DefaultAppointmentStorage);
diff --git a/BeWoPlanerMobil/Views/DevExpressScheduler/VerticalAppointmentTemplatePartial.cshtml b/BeWoPlanerMobil/Views/DevExpressScheduler/VerticalAppointmentTemplatePartial.cshtml
index 208f4bade..c5594adec 100644
--- a/BeWoPlanerMobil/Views/DevExpressScheduler/VerticalAppointmentTemplatePartial.cshtml
+++ b/BeWoPlanerMobil/Views/DevExpressScheduler/VerticalAppointmentTemplatePartial.cshtml
@@ -4,15 +4,9 @@
 @model AppointmentViewInfo
 
 @functions{
-	string GetHeaderText(){
-		return $"{Model.AppointmentInterval.Start.ToShortTimeString()} - {Model.Appointment.End.ToShortTimeString()}";
-	}
-
-	string GetRight()
+	string GetHeaderText()
 	{
-        var serviceRecords = Model.Appointment.CustomFields[nameof(SchedulerAppointmentDC.ServiceRecordList)] as List<ServiceRecordDC> ?? new List<ServiceRecordDC>();
-
-        return serviceRecords.Any() ? "40px" : "23px";
+		return $"{Model.AppointmentInterval.Start.ToShortTimeString()} - {Model.Appointment.End.ToShortTimeString()}";
 	}
 }
 
@@ -65,7 +59,7 @@
             {
                 if(Model.Appointment.Id is long)
                 {
-                    <span class="fa-stack fa-1x text-info float-right" style="height:fit-content;width:fit-content;position:absolute;top:10px;right:@GetRight();">
+                    <span class="fa-stack fa-1x text-info float-right" style="height:fit-content;width:fit-content;position:absolute;top:10px;right:@MobileUtils.GetCssRightValue(Model.Appointment);">
                         <i class="fas fa-solid fa-stack-1x fa-slash"></i>
                         <i class="fas fa-solid fa-stack-1x fa-sync-alt"></i>
                     </span>
diff --git a/BeWoPlanerMobil/Views/Shared/AbsenceTimeFormPartial.cshtml b/BeWoPlanerMobil/Views/Shared/AbsenceTimeFormPartial.cshtml
index 0974ac116..36ad9e333 100644
--- a/BeWoPlanerMobil/Views/Shared/AbsenceTimeFormPartial.cshtml
+++ b/BeWoPlanerMobil/Views/Shared/AbsenceTimeFormPartial.cshtml
@@ -35,17 +35,8 @@
 
 			let validationMessage = "";
 
-			const allDay = $(`#@Model.HtmlPrefix-absence-time-allday-cb`).is(":checked");
-
-			const startDateString = $(`#@Model.HtmlPrefix-absence-time-start-date-input`).val();
-			const endDateString = $(`#@Model.HtmlPrefix-absence-time-end-date-input`).val();     // z.B. 2025-05-20
-			const startTimeString = $(`#@Model.HtmlPrefix-absence-time-start-time-input`).val(); // z.B. 09:17
-			const endTimeString = $(`#@Model.HtmlPrefix-absence-time-end-time-input`).val();
-
-			const isInfinite = endDateString.length === 0 && endTimeString.length === 0;
-
-			const start = allDay ? new Date(startDateString) : combineDateAndTime(new Date(startDateString), startTimeString);
-			const end = allDay ? new Date(endDateString) : combineDateAndTime(new Date(endDateString), endTimeString);
+			const startAndEnd = getStartAndEndAndIfInfinite();
+			const [start, end, isInfinite] = startAndEnd;
 
 			const isStartValid = false === isNaN(start.getTime());
 			const isEndValid = false === isNaN(end.getTime()) || isInfinite;
@@ -74,6 +65,22 @@
 		}
 	}
 
+	function getStartAndEndAndIfInfinite() {
+		const allDay = $(`#@Model.HtmlPrefix-absence-time-allday-cb`).is(":checked");
+
+		const startDateString = $(`#@Model.HtmlPrefix-absence-time-start-date-input`).val();
+		const endDateString = $(`#@Model.HtmlPrefix-absence-time-end-date-input`).val();     // z.B. 2025-05-20
+		const startTimeString = $(`#@Model.HtmlPrefix-absence-time-start-time-input`).val(); // z.B. 09:17
+		const endTimeString = $(`#@Model.HtmlPrefix-absence-time-end-time-input`).val();
+
+		const isInfinite = endDateString.length === 0 && endTimeString.length === 0;
+
+        const start = allDay ? new Date(`${startDateString}T00:00`) : combineDateAndTime(new Date(startDateString), startTimeString);
+		const end = allDay ? new Date(`${endDateString}T00:00`) : combineDateAndTime(new Date(endDateString), endTimeString);
+
+        return [start, end, isInfinite];
+	}
+
 	function toggleAllDay() {
 		try {
 			const checkbox = $(`#@Model.HtmlPrefix-absence-time-allday-cb`);
@@ -100,9 +107,47 @@
 				return;
 			}
 
-			showSpinner();
-			$("#create-absence-time-form").submit();
-			$(`#@Model.HtmlPrefix-absence-times-form-popup`).modal("hide");
+            const [start, end] = getStartAndEndAndIfInfinite();
+
+			$.get("@Url.Action("CheckForOverlappingAbsenceTimes", controllerName)",
+				{
+					startStr: getUnixTimeStamp(start, true, false),
+					endStr: getUnixTimeStamp(end, true, false),
+					oid: @Model.AbsenteeOid
+				}
+			).done(
+				function(messagesJson) {
+					const messages = JSON.parse(messagesJson);
+
+					if(messages.length === 0) {
+						showSpinner();
+						$("#create-absence-time-form").submit();
+						$(`#@Model.HtmlPrefix-absence-times-form-popup`).modal("hide");
+					} else {
+						$(`#@Model.HtmlPrefix-absence-times-form-popup`).modal("hide");
+
+						let messagesStr = "";
+
+						for(let i = 0; i < messages.length; i++) {
+							messagesStr += messages[i];
+						}
+
+						showMessagePopupWithHtmlAndCallbacks(
+							"BeWoPlaner",
+							messagesStr,
+							() => {
+								showSpinner();
+								$("#create-absence-time-form").submit();
+								$(`#@Model.HtmlPrefix-absence-times-form-popup`).modal("hide");
+							},
+							() => {
+								$("#messagePopup").modal("hide");
+								$(`#@Model.HtmlPrefix-absence-times-form-popup`).modal("show");
+							}
+						);
+					}
+				}
+			);
 		} catch(error) {
 			showErrorPopup(error);
 		}
diff --git a/BeWoPlanerMobil/Views/Shared/_Layout.cshtml b/BeWoPlanerMobil/Views/Shared/_Layout.cshtml
index d3d67b23a..a1137d66f 100644
--- a/BeWoPlanerMobil/Views/Shared/_Layout.cshtml
+++ b/BeWoPlanerMobil/Views/Shared/_Layout.cshtml
@@ -53,7 +53,7 @@
 
     <script type="text/javascript" src="@Scripts.Url("~/Scripts/moment/moment.min.js")"></script>
     <script type="text/javascript" src="@Scripts.Url("~/Scripts/moment/locale/de.js")"></script>
-    <script type="text/javascript" src="@Scripts.Url("~/Scripts/ownSoft-Scripts/mobileUtils.js?v=1.8")"></script>
+    <script type="text/javascript" src="@Scripts.Url("~/Scripts/ownSoft-Scripts/mobileUtils.js?v=1.9")"></script>
 
     <script type="text/javascript" src="@Scripts.Url("~/Scripts/ownSoft-Scripts/view-scripts/main.js?v=2.6")"></script>
     <script type="text/javascript" src="@Scripts.Url("~/Scripts/ownSoft-Scripts/signature.js?v=1.5")"></script>
@@ -375,7 +375,7 @@
                             {
                                 <li class="nav-item">
                                     <button class="btn btn-link text-light no-underline" onclick="showSpinner()">
-                                        <i class="fas fa-hammer" style="color: #FFD9C2;"></i>
+                                        <i class="far fa-calendar-alt text-bewo-calendar"></i>
                                         DX Kalender
                                     </button>
                                 </li>
diff --git a/Data/Access/SearchDAO.cs b/Data/Access/SearchDAO.cs
index 1434afe80..b54da9659 100644
--- a/Data/Access/SearchDAO.cs
+++ b/Data/Access/SearchDAO.cs
@@ -3678,7 +3678,9 @@ WHERE sc.Billable = 1 and sr.StartDate >= '{0:yyyy-MM-dd}' and sr.StartDate < '{
 		{
 			var c = CreateCriteria<AbsenceTime>();
 
-			var peopleRestriction = employeeOid != null ? Restrictions.Eq(nameof(AbsenceTime.EmployeeOid), employeeOid) : Restrictions.Eq(nameof(AbsenceTime.CustomerOid), customerOid);
+			var peopleRestriction = employeeOid != null ? 
+                Restrictions.Eq(nameof(AbsenceTime.EmployeeOid), employeeOid) : 
+                Restrictions.Eq(nameof(AbsenceTime.CustomerOid), customerOid);
 
 			var timeRestriction = CreateBetweenDateTimesCriterion(startDate, endDate, nameof(AbsenceTime.Start), nameof(AbsenceTime.End));
 
diff --git a/Service/Plugins/OperationService.cs b/Service/Plugins/OperationService.cs
index f906177e2..d9b1a995b 100644
--- a/Service/Plugins/OperationService.cs
+++ b/Service/Plugins/OperationService.cs
@@ -457,7 +457,12 @@ namespace BeWo.Service.Plugins
             return list.OrderBy(t => t.Name).ToList();
         }
 
+        public bool CheckForOverlappingAbsenceTimes(DateTime? start, DateTime? end, long? employeeOid, long? customerOid)
+        {
+            var startValue = start ?? DateTime.MinValue;
+            var endValue = end ?? DateTime.MaxValue;
 
-        
+            return DAOFactory.SearchDAO.CheckForOverlappingAbsenceTimes(startValue, endValue, employeeOid, customerOid);
+        }
     }
 }
\ No newline at end of file
diff --git a/Service/ServiceImplementations/OperationsServiceImp.cs b/Service/ServiceImplementations/OperationsServiceImp.cs
index e9826ae64..974643e7a 100644
--- a/Service/ServiceImplementations/OperationsServiceImp.cs
+++ b/Service/ServiceImplementations/OperationsServiceImp.cs
@@ -9093,5 +9093,4 @@ namespace BeWo.Service.ServiceImplementations
             }
         }
     }
-
 }
diff --git a/Shared/DataContracts/SchedulerAppointmentDC.cs b/Shared/DataContracts/SchedulerAppointmentDC.cs
index 2d1ce0b3e..ab1120e3b 100644
--- a/Shared/DataContracts/SchedulerAppointmentDC.cs
+++ b/Shared/DataContracts/SchedulerAppointmentDC.cs
@@ -221,5 +221,33 @@ namespace BS.Shared.DataContracts
 		}
 
         public override string ToString() => $"{SchedulerAppointmentOid} {StartDate:dd.MM.yyyy HH:mm}-{EndDate:dd.MM.yyyy HH:mm}: {Subject}";
+
+        public static SchedulerAppointmentDC RecurringExceptionFromDevExpressAppointment(Appointment appointment, SchedulerAppointmentDC baseAppointment)
+        {
+            return new SchedulerAppointmentDC
+            {
+                ActivationType           = ActivationTypeId.Active,
+				Subject                  = baseAppointment.Subject,
+				Description              = baseAppointment.Description,
+				CustomerList             = baseAppointment.CustomerList,
+				Originator               = baseAppointment.Originator,
+				EmployeeList             = baseAppointment.EmployeeList,
+				ResourceList             = baseAppointment.ResourceList,
+                AllDay                   = baseAppointment.AllDay,
+                CanBeEdited              = baseAppointment.CanBeEdited,
+                FormerBookingSequenceOid = baseAppointment.FormerBookingSequenceOid,
+                IsPrivate                = baseAppointment.IsPrivate,
+                Location                 = baseAppointment.Location,
+				StartDate                = appointment.Start,
+				EndDate                  = appointment.End,
+                RecurrenceId             = appointment.RecurrenceInfo.Id.ToString(),
+                LabelKey                 = (long?) appointment.LabelKey,
+                RecurrenceIndex          = appointment.RecurrenceIndex,
+                RecurrenceInfo           = appointment.RecurrenceInfo.ToXml(),
+                Type                     = (int) appointment.Type,
+                SupportConceptList       = baseAppointment.SupportConceptList,
+				ServiceRecordList        = baseAppointment.ServiceRecordList
+            };
+        }
     }
 }