diff --git a/frontend/pages/communication/chat.vue b/frontend/pages/communication/chat.vue
index 2f8f86d..24226f0 100644
--- a/frontend/pages/communication/chat.vue
+++ b/frontend/pages/communication/chat.vue
@@ -70,6 +70,7 @@ let matrixLiveKitRoom = null
 let matrixLiveSyncRunId = 0
 const matrixCallVideoElements = new Map()
 const matrixAttachmentPreviewRequests = new Set()
+const matrixAttachmentPreviewFailures = new Set()
 const matrixSyncSince = ref("")
 
 const canUseMatrixChat = computed(() =>
@@ -1388,7 +1389,12 @@ const attachmentObjectUrl = (attachment) =>
   attachment?.url ? matrixAttachmentObjectUrls.value[attachment.url] || "" : ""
 
 const ensureAttachmentObjectUrl = async (attachment) => {
-  if (!attachment?.url || matrixAttachmentObjectUrls.value[attachment.url] || matrixAttachmentPreviewRequests.has(attachment.url)) return
+  if (
+    !attachment?.url ||
+    matrixAttachmentObjectUrls.value[attachment.url] ||
+    matrixAttachmentPreviewRequests.has(attachment.url) ||
+    matrixAttachmentPreviewFailures.has(attachment.url)
+  ) return
 
   matrixAttachmentPreviewRequests.add(attachment.url)
   try {
@@ -1401,6 +1407,7 @@ const ensureAttachmentObjectUrl = async (attachment) => {
       [attachment.url]: objectUrl
     }
   } catch (error) {
+    matrixAttachmentPreviewFailures.add(attachment.url)
     // Fällt nur auf den Link zurück; der Chat selbst soll weiter funktionieren.
   } finally {
     matrixAttachmentPreviewRequests.delete(attachment.url)