用于操纵Azure blob容器的共享访问签名

我希望将SAS URI提供给其他应用程序,以允许它们将文件发送到blob容器。但是,当尝试上载文件时,代码失败,导致出现异常,其中指出:

服务器无法验证请求。确保包括签名在内的授权标头的值格式正确。

我正在使用aspnetcore和WindowsAzure。存储版本9.1.0。

        var acc = CloudStorageAccount.Parse("mysecrets");
        CloudBlobClient client = acc.CreateCloudBlobClient();
        var container = client.GetContainerReference("myblobcontainer");
        await container.CreateIfNotExistsAsync();
        var permissions = container.GetPermissionsAsync().Result;
        permissions.SharedAccessPolicies.Add("writepolicy",
            new SharedAccessBlobPolicy
            {
                Permissions =
                    SharedAccessBlobPermissions.Add |
                    SharedAccessBlobPermissions.Create |
                    SharedAccessBlobPermissions.List |
                    SharedAccessBlobPermissions.Write,
            });
        await container.SetPermissionsAsync(permissions);
        var sas = container.GetSharedAccessSignature(null, "writepolicy");
        var accessUri = container.Uri.ToString() + sas;

        var cloudBlobContainer = new CloudBlobContainer(new Uri(accessUri));
        var blob = cloudBlobContainer.GetBlockBlobReference("myfile.txt");
        await blob.UploadFromFileAsync("foo.txt");

我也尝试过这样创建cloudBlobContainer:

var cloudBlobContainer = 
             new CloudBlobContainer(container.Uri, new StorageCredentials(sas));