diff --git a/desktop/src/features/messages/lib/backgroundMediaUploadStore.test.mjs b/desktop/src/features/messages/lib/backgroundMediaUploadStore.test.mjs
index 2a4366be5..da13cb70d 100644
--- a/desktop/src/features/messages/lib/backgroundMediaUploadStore.test.mjs
+++ b/desktop/src/features/messages/lib/backgroundMediaUploadStore.test.mjs
@@ -4,6 +4,7 @@ import test from "node:test";
 import {
   cancelStartedMediaUploads,
   dispatchTrackedMediaUpload,
+  prepareBackgroundMediaUpload,
 } from "./backgroundMediaUploadStore.ts";
 
 const descriptor = {
@@ -22,6 +23,27 @@ function deferred() {
   return { promise, resolve };
 }
 
+test("reports cancellation before a prepared upload starts", () => {
+  const prepared = prepareBackgroundMediaUpload([
+    {
+      file: new File(["video"], "large-video.mp4", { type: "video/mp4" }),
+      id: 1,
+      spoilered: false,
+    },
+  ]);
+
+  assert.equal(prepared.isCanceled(), false);
+  prepared.cancel();
+  assert.equal(prepared.isCanceled(), true);
+  assert.equal(
+    prepared.start({
+      onComplete: async () => {},
+      onError: () => {},
+    }),
+    false,
+  );
+});
+
 test("cancels only uploads whose native commands were dispatched", async () => {
   const releaseUpload = deferred();
   const startedProgressIds = new Map();
diff --git a/desktop/src/features/messages/lib/backgroundMediaUploadStore.ts b/desktop/src/features/messages/lib/backgroundMediaUploadStore.ts
index 806692606..3f7bd5a91 100644
--- a/desktop/src/features/messages/lib/backgroundMediaUploadStore.ts
+++ b/desktop/src/features/messages/lib/backgroundMediaUploadStore.ts
@@ -54,6 +54,7 @@ type StartBackgroundUploadOptions = Omit<
 
 export type PreparedBackgroundMediaUpload = {
   cancel: () => void;
+  isCanceled: () => boolean;
   start: (options: StartBackgroundUploadOptions) => boolean;
 };
 
@@ -243,6 +244,7 @@ export function prepareBackgroundMediaUpload(
     let started = false;
     return {
       cancel: () => undefined,
+      isCanceled: () => false,
       start: ({ onComplete, onError }) => {
         if (started) return false;
         started = true;
@@ -274,6 +276,7 @@ export function prepareBackgroundMediaUpload(
     cancel: () => {
       cancelTask(task);
     },
+    isCanceled: () => task.canceled,
     start: ({ onCancel, onComplete, onError }) => {
       if (started || task.canceled) return false;
       started = true;
diff --git a/desktop/src/features/messages/ui/useMentionSendFlow.ts b/desktop/src/features/messages/ui/useMentionSendFlow.ts
index 5842ad42c..e17ee66f3 100644
--- a/desktop/src/features/messages/ui/useMentionSendFlow.ts
+++ b/desktop/src/features/messages/ui/useMentionSendFlow.ts
@@ -572,7 +572,7 @@ export function useMentionSendFlow({
             );
           }
         };
-        if (!optimisticId && sendChannelId) {
+        if (!optimisticId && sendChannelId && !preparedUpload?.isCanceled()) {
           const initialMessage = buildOutgoingMessage(
             draft.trimmed,
             draft.savedImeta,
@@ -621,9 +621,7 @@ export function useMentionSendFlow({
               restoreComposerAfterFailure();
             },
           });
-          if (!uploadStarted) {
-            return;
-          }
+          if (!uploadStarted) return removePendingSend();
         }
         if (
           draft.capturedChannelId === channelIdRef.current ||
diff --git a/desktop/tests/e2e/file-attachment.spec.ts b/desktop/tests/e2e/file-attachment.spec.ts
index 93ae28054..b2ecef5a0 100644
--- a/desktop/tests/e2e/file-attachment.spec.ts
+++ b/desktop/tests/e2e/file-attachment.spec.ts
@@ -265,6 +265,12 @@ test("sends immediately and keeps upload progress across channels", async ({
   await expect(queuedSpoiler).toHaveCSS("opacity", "1");
   await page.getByTestId("send-message").click();
 
+  const pendingRow = page.getByTestId("message-row").last();
+  await expect(
+    pendingRow.getByTestId("message-preparation-status"),
+  ).toContainText("Preparing large-video.mp4…");
+  const pendingMessageId = await pendingRow.getAttribute("data-message-id");
+  expect(pendingMessageId).not.toBeNull();
   await expect(page.getByTestId("message-composer")).not.toContainText(
     "large-video.mp4",
   );
@@ -278,6 +284,9 @@ test("sends immediately and keeps upload progress across channels", async ({
   });
 
   await page.getByTestId("channel-general").click();
+  await expect(
+    page.locator(`[data-message-id="${pendingMessageId}"]`),
+  ).toHaveCount(1);
   await expect(page.getByTestId("file-card").last()).toContainText(
     "quarterly-report.pdf",
   );