I am unable to upload a file using azure-blob js sdk given a sas token

Question

When trying to upload via JS, I get this error:

RestError: Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature.

RequestId:a441c1f7-001e-0021-2b0b-bad5b1000000

Why? Here is the sas url: https://zcast.blob.core.windows.net/episodes/temp-queued-files/PvweJkDoRT.mp3?sv=2023-08-03&st=2025-04-30T20%3A04%3A39Z&se=2025-05-01T20%3A04%3A39Z&sr=b&sp=racw&sig=dYv

Answer 1

Hi @Ian Davis

Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature

The above error occurs when your Azure Blob Storage rejected your request due to an invalid or improperly formatted Shared Access Signature (SAS) token.

You can use the below code which will create Shared Access Signature (SAS) token and will upload the file in the Azure Blob storage using Azure JavaScript SDK.

Code:

// Replace with your own values
const accountName = "xxxxx";
const accountKey = "xxxxx";
const containerName = "xxx";
const blobName = "test/PvweJkDoRT.mp3";
const filePath = "xxxxxxx";

const sharedKeyCredential = new StorageSharedKeyCredential(accountName, accountKey);
const blobServiceClient = new BlobServiceClient(
  `https://${accountName}.blob.core.windows.net`,
  sharedKeyCredential
);
const containerClient = blobServiceClient.getContainerClient(containerName);

function getBlobSasUri(containerClient, blobName, sharedKeyCredential, storedPolicyName = null) {
  const sasOptions = {
    containerName: containerClient.containerName,
    blobName: blobName
  };

  if (storedPolicyName == null) {
    sasOptions.startsOn = new Date();
    sasOptions.expiresOn = new Date(new Date().valueOf() + 3600 * 1000); // 1 hour
    sasOptions.permissions = BlobSASPermissions.parse("cw"); // create + write
  } else {
    sasOptions.identifier = storedPolicyName;
  }

  const sasToken = generateBlobSASQueryParameters(sasOptions, sharedKeyCredential).toString();
  return `${containerClient.getBlockBlobClient(blobName).url}?${sasToken}`;
}

// Upload the file using fetch + PUT + SAS URL
async function uploadViaSasUrl(sasUrl, filePath) {
  const fileBuffer = fs.readFileSync(filePath);
  const fileSize = fs.statSync(filePath).size;

  const response = await fetch(sasUrl, {
    method: "PUT",
    headers: {
      "x-ms-blob-type": "BlockBlob",
      "Content-Length": fileSize,
      "Content-Type": "audio/mpeg"
    },
    body: fileBuffer
  });

  if (response.ok) {
    console.log("Upload successful.");
  } else {
    const errText = await response.text();
    console.error("Upload failed:", response.status, errText);
  }
}

(async () => {
  const sasUrl = getBlobSasUri(containerClient, blobName, sharedKeyCredential);
  console.log("SAS URL:", sasUrl);
  await uploadViaSasUrl(sasUrl, filePath);
})();

Output:

Portal:

Reference:

Create a service SAS for a container or blob with JavaScript - Azure Storage | Microsoft Learn

Hope this answer helps! please let us know if you have any further queries. I’m happy to assist you further.

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