diff --git a/e2e/storage/helpers.ts b/e2e/storage/helpers.ts
index 02a7fe25..d750d9a2 100644
--- a/e2e/storage/helpers.ts
+++ b/e2e/storage/helpers.ts
@@ -206,7 +206,10 @@ export async function putTextObject(
 }
 
 export async function putDirectoryMarker(client: S3Client, bucket: string, key: string) {
-  await client.send(new PutObjectCommand({ Bucket: bucket, Key: key, Body: '' }));
+  // The SDK sets no Content-Length for a falsy body, so '' triggers its stream warning.
+  await client.send(
+    new PutObjectCommand({ Bucket: bucket, Key: key, Body: Buffer.alloc(0), ContentLength: 0 })
+  );
 }
 
 export async function deleteKnownKeys(client: S3Client, bucket: string, keys: string[]) {
diff --git a/e2e/storage/upload.spec.ts b/e2e/storage/upload.spec.ts
index e8c0b050..d724796b 100644
--- a/e2e/storage/upload.spec.ts
+++ b/e2e/storage/upload.spec.ts
@@ -346,7 +346,8 @@ test.describe('Storage S3 — Upload', () => {
       const warning = page.getByRole('dialog', { name: 'Upload in progress' });
       await page.goBack();
       await expect(warning).toBeVisible();
-      expect(page.url()).toBe(browseUrl);
+      // SvelteKit restores the URL of a cancelled Back asynchronously.
+      await expect(page).toHaveURL(browseUrl);
       await warning.getByRole('button', { name: 'Stay' }).click();
       await expect(warning).toBeHidden();
       await expect(page.getByRole('heading', { name: 'Upload', exact: true })).toBeVisible();
diff --git a/e2e/support/garage.ts b/e2e/support/garage.ts
index 9989bf78..2cd8a3eb 100644
--- a/e2e/support/garage.ts
+++ b/e2e/support/garage.ts
@@ -152,7 +152,17 @@ async function ensureBucket(bucketName: string): Promise<string> {
     return existingId;
   }
 
-  const created = await adminPost('/v2/CreateBucket', { globalAlias: bucketName });
+  let created: unknown;
+  try {
+    created = await adminPost('/v2/CreateBucket', { globalAlias: bucketName });
+  } catch (err) {
+    // Another worker may have created the bucket since the lookup above.
+    const racedId = await findBucketId(bucketName);
+    if (racedId) {
+      return racedId;
+    }
+    throw err;
+  }
   const createdId = readString(created, ['id', 'bucketId', 'bucket_id']);
 
   if (createdId) {