diff --git a/src/components/ConversationIcon.vue b/src/components/ConversationIcon.vue
index bed942122c..785b639e1a 100644
--- a/src/components/ConversationIcon.vue
+++ b/src/components/ConversationIcon.vue
@@ -174,8 +174,17 @@ export default {
 			return getPreloadedUserStatus(this.item)
 		},
 
+		canRequestAvatar() {
+			if (!supportsAvatar || this.item.isDummyConversation) {
+				return false
+			}
+
+			// Endpoint limited with #RequireParticipantOrLoggedInAndListedConversation
+			return !!this.item.actorId
+		},
+
 		iconClass() {
-			return getFallbackIconClass(this.item, this.failed)
+			return getFallbackIconClass(this.item, this.failed || !this.canRequestAvatar)
 		},
 
 		themeClass() {
@@ -196,7 +205,7 @@ export default {
 		},
 
 		avatarUrl() {
-			if (!supportsAvatar || this.item.isDummyConversation) {
+			if (!this.canRequestAvatar) {
 				return undefined
 			}
 
diff --git a/src/components/RightSidebar/RightSidebarContent.vue b/src/components/RightSidebar/RightSidebarContent.vue
index cebc032304..12476d5d1d 100644
--- a/src/components/RightSidebar/RightSidebarContent.vue
+++ b/src/components/RightSidebar/RightSidebarContent.vue
@@ -30,6 +30,7 @@ import LocalTime from '../UIShared/LocalTime.vue'
 import { useGetToken } from '../../composables/useGetToken.ts'
 import { CONVERSATION } from '../../constants.ts'
 import { getConversationAvatarOcsUrl } from '../../services/avatarService.ts'
+import { hasTalkFeature } from '../../services/CapabilitiesManager.ts'
 import { useGroupwareStore } from '../../stores/groupware.ts'
 import { getFallbackIconClass } from '../../utils/conversation.ts'
 import { convertToUnix } from '../../utils/formattedTime.ts'
@@ -55,6 +56,8 @@ const emit = defineEmits<{
 	(event: 'update:mode', value: 'compact' | 'preview' | 'full'): void
 }>()
 
+const supportsAvatar = hasTalkFeature('local', 'avatar')
+
 const store = useStore()
 const groupwareStore = useGroupwareStore()
 
@@ -93,10 +96,19 @@ const sidebarTitle = computed(() => {
 	return conversation.value.displayName
 })
 
-const iconClass = computed(() => getFallbackIconClass(conversation.value, profileImageFailed.value))
+const canRequestAvatar = computed(() => {
+	if (!supportsAvatar || conversation.value.isDummyConversation) {
+		return false
+	}
+
+	// Endpoint limited with #RequireParticipantOrLoggedInAndListedConversation
+	return !!conversation.value.actorId
+})
+
+const iconClass = computed(() => getFallbackIconClass(conversation.value, (profileImageFailed.value || !canRequestAvatar.value)))
 
 const avatarUrl = computed(() => {
-	if (iconClass.value) {
+	if (iconClass.value || !canRequestAvatar.value) {
 		return undefined
 	}