Simple UploadPage azure blob using pageBlobClient - azure

Question

I am using Premium/Hot, LRS, StorageV2 Azure storage and trying to write a simple string but I keep getting an authentication error.
To generate the SAS URI of the container in the portal, I went to:
storage resource -> containers -> my container -> shared access token -> generate SAS token and URL
// SAS URI of blob container
var sasUriStr = "https://storageaccountname.blob.core.windows.net/containername?sp=r&st=2021-08-10T00:34:00Z&se=2021-08-15T08:34:00Z&spr=https&sv=2020-08-04&sr=c&sig=ABCDEFGH/YJKLMNOP=";
var uri = new Uri(sasUriStr);
var pageBlobClient = new PageBlobClient(uri);
pageBlobClient.UploadPages(new MemoryStream(Encoding.UTF8.GetBytes("hello world")), 0);
Unhandled exception. Azure.RequestFailedException: Server failed to
authenticate the request. Make sure the value of Authorization header
is formed correctly including the signature.
Time:2021-08-12T20:22:44.0905117Z Status: 403 (Server failed to
authenticate the request. Make sure the value of Authorization header
is formed correctly including the signature.) ErrorCode:
AuthenticationFailed
Additional Information: AuthenticationErrorDetail: Signature did not
match. String to sign used was r
I appreciate any help or hint. Thank you
UPDATE:
After adding /blob name to SAS URI I get this error:
Unhandled exception. Azure.RequestFailedException: The value for one of the HTTP headers is not in the correct format.
RequestId:7a741951-401c-00c9-3ce3-8f5076000000
Time:2021-08-13T01:38:13.4585107Z
Status: 400 (The value for one of the HTTP headers is not in the correct format.)
ErrorCode: InvalidHeaderValue
Additional Information:
HeaderName: x-ms-range
HeaderValue: bytes=0-10
Content:
<?xml version="1.0" encoding="utf-8"?>
<Error><Code>InvalidHeaderValue</Code><Message>The value for one of the HTTP headers is not in the correct format.
RequestId:7a741951-401c-00c9-3ce3-8f5076000000
Time:2021-08-13T01:38:13.4585107Z</Message><HeaderName>x-ms-range</HeaderName><HeaderValue>bytes=0-10</HeaderValue></Error>
Headers:
Server: Windows-Azure-Blob/1.0,Microsoft-HTTPAPI/2.0
x-ms-error-code: InvalidHeaderValue
x-ms-request-id: 7a741951-401c-00c9-3ce3-8f5076000000
x-ms-version: 2020-08-04
x-ms-client-request-id: 4366d771-7f70-4bbf-9677-6e9fcf3cb7a1
Date: Fri, 13 Aug 2021 01:38:12 GMT
Content-Length: 327
Content-Type: application/xml

Answer 1

Solution
Please change your code to something like:
var sasUriStr = "https://storageaccountname.blob.core.windows.net/containername?sp=r&st=2021-08-10T00:34:00Z&se=2021-08-15T08:34:00Z&spr=https&sv=2020-08-04&sr=c&sig=ABCDEFGH/YJKLMNOP=";
var uri = new Uri(sasUriStr);
BlobContainerClient containerClient = new BlobContainerClient(uri);
var pageBlobClient = containerClient.GetPageBlobClientCore("page-blob-name");
pageBlobClient.UploadPages(new MemoryStream(Encoding.UTF8.GetBytes("hello world")), 0);
Please ensure that the blob already exists before you use this code.
Problem
The reason you were running into the problem is because you were trying to create a PageBlobClient using a URI representing a blob container SAS. Because of this, Azure Storage service assumed that your blob name is containername and the container is $root. Since the SAS token was obtained for containername blob container and the service used $root blob container for validating the SAS token, you are getting authorization failed error.
By creating a BlobContainerClient using the SAS URL and then creating a PageBlobClient using BlobContainerClient.GetPageBlobClientCore(String) solves the problem.