diff --git a/src/components/events/partials/ModalTabsAndPages/NewSourcePage.tsx b/src/components/events/partials/ModalTabsAndPages/NewSourcePage.tsx
index 2bfedc4ae3..c588b522b3 100644
--- a/src/components/events/partials/ModalTabsAndPages/NewSourcePage.tsx
+++ b/src/components/events/partials/ModalTabsAndPages/NewSourcePage.tsx
@@ -12,7 +12,7 @@ import { Field } from "../../../shared/Field";
 import RenderField from "../../../shared/wizard/RenderField";
 import { getRecordings } from "../../../../selectors/recordingSelectors";
 import { sourceMetadata } from "../../../../configs/sourceConfig";
-import { weekdays } from "../../../../configs/modalConfig";
+import { weekdays, NOTIFICATION_CONTEXT } from "../../../../configs/modalConfig";
 import { getUserInformation } from "../../../../selectors/userInfoSelectors";
 import {
 	filterDevicesForAccess,
@@ -37,7 +37,7 @@ import {
 } from "../../../../utils/dateUtils";
 import { useAppDispatch, useAppSelector } from "../../../../store";
 import { Recording, fetchRecordings } from "../../../../slices/recordingSlice";
-import { removeNotificationWizardForm } from "../../../../slices/notificationSlice";
+import { addNotification, removeNotificationWizardForm } from "../../../../slices/notificationSlice";
 import { parseISO } from "date-fns";
 import WizardNavigationButtons from "../../../shared/wizard/WizardNavigationButtons";
 import { checkConflicts, UploadAssetsTrack } from "../../../../slices/eventSlice";
@@ -370,6 +370,23 @@ const Schedule = <T extends {
 }) => {
 	const { t } = useTranslation();
 	const currentLanguage = getCurrentLanguageInformation();
+	const dispatch = useAppDispatch();
+
+	// Parse start-Date strings
+	const startDateTime = new Date(
+	  `${new Date(formik.values.scheduleStartDate).toISOString().split("T")[0]}T${formik.values.scheduleStartHour}:${formik.values.scheduleStartMinute}:00`,
+	);
+
+	// Parse end datetime
+	const endDateTime = new Date(
+	  `${new Date(formik.values.scheduleEndDate).toISOString().split("T")[0]}T${formik.values.scheduleEndHour}:${formik.values.scheduleEndMinute}:00`,
+	);
+
+	const now = new Date();
+
+	// Event is in progress
+	const eventInProgress = now >= startDateTime && now <= endDateTime;
+
 	const getEndDateForSchedulingTime = () => {
 		const {
 			scheduleStartDate,
@@ -631,6 +648,17 @@ const Schedule = <T extends {
 							hourPlaceholder={"EVENTS.EVENTS.DETAILS.SOURCE.PLACEHOLDER.HOUR"}
 							minutePlaceholder={"EVENTS.EVENTS.DETAILS.SOURCE.PLACEHOLDER.MINUTE"}
 							callbackHour={(value: string) => {
+							if (eventInProgress && value < formik.values.scheduleEndHour) {
+							dispatch(
+							addNotification({
+							type: "error",
+							key: "CONFLICT_END_TIME_TOO_EARLY",
+							duration: -1,
+							context: NOTIFICATION_CONTEXT,
+							}),
+							);
+							return; // Block shortening
+							}
 								if (formik.values.sourceMode === "SCHEDULE_MULTIPLE") {
 									changeEndHourMultiple(
 										value,
@@ -646,6 +674,19 @@ const Schedule = <T extends {
 								}
 							}}
 							callbackMinute={(value: string) => {
+
+							if (eventInProgress && value < formik.values.scheduleEndMinute) {
+							dispatch(
+							addNotification({
+							type: "error",
+							key: "CONFLICT_END_TIME_TOO_EARLY",
+							duration: -1,
+							context: NOTIFICATION_CONTEXT,
+							}),
+							);
+							return; // Block shortening
+							}
+
 								if (formik.values.sourceMode === "SCHEDULE_MULTIPLE") {
 									changeEndMinuteMultiple(
 										value,
diff --git a/src/i18n/org/opencastproject/adminui/languages/lang-en_US.json b/src/i18n/org/opencastproject/adminui/languages/lang-en_US.json
index 4b2843ff91..03f650c94b 100644
--- a/src/i18n/org/opencastproject/adminui/languages/lang-en_US.json
+++ b/src/i18n/org/opencastproject/adminui/languages/lang-en_US.json
@@ -211,6 +211,7 @@
 		"CONFLICT_ALREADY_ENDED": "Scheduling error: The event has already ended.",
 		"CONFLICT_END_BEFORE_START": "Scheduling error: Schedule end has to be later than the start.",
 		"CONFLICT_IN_THE_PAST": "The schedule could not be updated: You cannot schedule an event to be in the past.",
+		"CONFLICT_END_TIME_TOO_EARLY": "This event cannot be modified because it is currently in progress.",
 		"CONFLICT_RANGE_DAYS":"At least one repeat day must be within the scheduled date range.",
 		"INVALID_ACL_RULES": "Rules have to contain a valid role and read or/and write right(s).",
 		"MISSING_ACL_RULES": "At least one role with Read and Write permissions is required!",
diff --git a/src/slices/eventSlice.ts b/src/slices/eventSlice.ts
index baa4a318bc..4196dffff3 100644
--- a/src/slices/eventSlice.ts
+++ b/src/slices/eventSlice.ts
@@ -904,7 +904,6 @@ export const checkConflicts = (values: {
 	sourceMode: string,
 }) => async (dispatch: AppDispatch) => {
 	let check = true;
-
 	// Only perform checks if source mode is SCHEDULE_SINGLE or SCHEDULE_MULTIPLE
 	if (
 		values.sourceMode === "SCHEDULE_SINGLE" ||
@@ -936,7 +935,8 @@ export const checkConflicts = (values: {
 			0,
 			0,
 		);
-
+		const today = new Date();
+		today.setHours(0, 0, 0, 0);
 		// If start date of event is smaller than today --> Event is in past
 		if ((values.sourceMode === "SCHEDULE_SINGLE" && startDate < new Date()) || (values.sourceMode === "SCHEDULE_MULTIPLE" && startDate < new Date())) {
 			dispatch(