diff --git a/src/api/media-upload-contracts.ts b/src/api/media-upload-contracts.ts
index baf1663a..7a4644d1 100644
--- a/src/api/media-upload-contracts.ts
+++ b/src/api/media-upload-contracts.ts
@@ -88,6 +88,9 @@ export function safeMediaUploadErrorMessage(error: Error): string {
   if (error instanceof MediaUploadScanTimeoutError) {
     return "The upload is still processing. Check back shortly to see the result.";
   }
+  if (error instanceof MediaUploadCanceledError) {
+    return "The upload session was canceled.";
+  }
   if (error.name === "AbortError") {
     return "Upload canceled.";
   }
diff --git a/src/test/api/media-upload-engine.test.ts b/src/test/api/media-upload-engine.test.ts
index e06b9264..3f4bbc0a 100644
--- a/src/test/api/media-upload-engine.test.ts
+++ b/src/test/api/media-upload-engine.test.ts
@@ -9,6 +9,10 @@ import {
   uploadFileResumable,
 } from "@/api/media-upload-engine";
 import { computeSha256Hex, createMediaUploadEndpoints } from "@/api/media-upload-client";
+import {
+  MediaUploadCanceledError,
+  safeMediaUploadErrorMessage,
+} from "@/api/media-upload-contracts";
 
 type CapturedRequest = { method: string; url: string; headers: Headers; body: unknown };
 
@@ -500,6 +504,40 @@ describe("resumable media upload engine", () => {
   });
 });
 
+describe("safeMediaUploadErrorMessage", () => {
+  it("maps a server-canceled session to its own copy, distinct from a user abort", async () => {
+    const file = fileOf(8);
+    handler = async (request) => {
+      if (request.method === "POST" && request.url === BASE) {
+        return jsonResponse(createdSession(8, 8));
+      }
+      if (request.method === "PUT" && /chunks\/0$/.test(request.url)) {
+        return jsonResponse({ index: 0, sha256: "x", sizeBytes: 8, receivedChunks: [0] });
+      }
+      if (request.method === "POST" && request.url.endsWith("/commit")) {
+        return jsonResponse({ ...createdSession(8, 8), state: "Scanning" }, 202);
+      }
+      if (request.method === "GET" && request.url === `${BASE}/u1`) {
+        return jsonResponse({ ...createdSession(8, 8), state: "Canceled" });
+      }
+      return jsonResponse({});
+    };
+
+    const error = await uploadFileResumable({
+      file,
+      endpoints: endpointsWith(),
+      surface: "WorkOrderTable",
+      pollDelayMs: 0,
+    }).catch((caught: unknown) => caught);
+
+    expect(error).toBeInstanceOf(MediaUploadCanceledError);
+    expect(safeMediaUploadErrorMessage(error as Error)).toBe("The upload session was canceled.");
+    expect(safeMediaUploadErrorMessage(new DOMException("aborted", "AbortError"))).toBe(
+      "Upload canceled.",
+    );
+  });
+});
+
 describe("chunk math helpers", () => {
   it("computes chunk counts and missing indices", () => {
     expect(chunkCountFor(0, 5_242_880)).toBe(1);