diff --git a/src/addons/calendar/pages/edit-event/edit-event.page.ts b/src/addons/calendar/pages/edit-event/edit-event.page.ts
index d7bcfd094..c1807d35f 100644
--- a/src/addons/calendar/pages/edit-event/edit-event.page.ts
+++ b/src/addons/calendar/pages/edit-event/edit-event.page.ts
@@ -520,7 +520,7 @@ export class AddonCalendarEditEventPage implements OnInit, OnDestroy, CanLeave {
 
         try {
             const result = await AddonCalendar.submitEvent(this.eventId, data, {
-                reminders: this.reminders,
+                reminders: this.eventId ? [] : this.reminders, // Only allow adding reminders for new events.
             });
             event = result.event;
 
@@ -638,7 +638,8 @@ export class AddonCalendarEditEventPage implements OnInit, OnDestroy, CanLeave {
      * @return Promise resolved when done.
      */
     protected async initReminders(): Promise<void> {
-        if (!this.notificationsEnabled) {
+        // Don't init reminders when editing an event. Right now, only allow adding reminders for new events.
+        if (!this.notificationsEnabled || this.eventId) {
             return;
         }
 
diff --git a/src/addons/calendar/services/calendar.ts b/src/addons/calendar/services/calendar.ts
index ec8c8db11..817b44ee1 100644
--- a/src/addons/calendar/services/calendar.ts
+++ b/src/addons/calendar/services/calendar.ts
@@ -1696,7 +1696,7 @@ export class AddonCalendarProvider {
             const event = await AddonCalendarOffline.saveEvent(eventId, formData, siteId);
 
             // Now save the reminders if any.
-            if (options.reminders) {
+            if (options.reminders?.length) {
                 await CoreUtils.ignoreErrors(
                     Promise.all(options.reminders.map((reminder) => this.addEventReminder(event, reminder.time, siteId))),
                 );
@@ -1718,7 +1718,7 @@ export class AddonCalendarProvider {
             const event = await this.submitEventOnline(eventId, formData, siteId);
 
             // Now save the reminders if any.
-            if (options.reminders) {
+            if (options.reminders?.length) {
                 await CoreUtils.ignoreErrors(
                     Promise.all(options.reminders.map((reminder) => this.addEventReminder(event, reminder.time, siteId))),
                 );