404 for a small period of time after uploading file to Azure Blob Storage

I upload attachments to an Azure Blob storage. I also create a SAS-Token when uploading; I retrieve the unique URL, send it to the browser where it is opened immediatly.

When I do this I often (but not always) retrieve a 404 that this resource does not exist. When refreshing the page just a few seconds later it is retrieved correctly.

So it seems that I am "too fast" after uploading the attachment. Is there a way to wait until Azure is ready to serve the attachment? I would have expected awaiting the call would be sufficient to achieve this.

public async void UploadFile(string filename, byte[] filecontent)
{
    var containerClient = _blobServiceclient.GetBlobContainerClient("attachments");
    var blobClient = containerClient.GetBlobClient(filename);
    
    using (var stream = new MemoryStream(filecontent))
    {
      await blobClient.UploadAsync(stream, new BlobHttpHeaders { ContentType = GetContentTypeByFilename(filename) });
    }
}


  public async Task<string> GetLinkForFile(string filename)
{
    var containerClient = _blobServiceclient.GetBlobContainerClient("attachments");
    
    var sasBuilder = new BlobSasBuilder()
    {
        BlobContainerName = containerName,
        BlobName = filename,
        Resource = "b",
        StartsOn = DateTime.UtcNow.AddMinutes(-1),
        ExpiresOn = DateTime.UtcNow.AddMinutes(5),
    };

    // Specify read permissions
    sasBuilder.SetPermissions(BlobSasPermissions.Read);

    var credentials = new StorageSharedKeyCredential(_blobServiceclient.AccountName, _accountKey);
    var sasToken = sasBuilder.ToSasQueryParameters(credentials);

    // Construct the full URI, including the SAS token.
    UriBuilder fullUri = new UriBuilder()
    {
        Scheme = "https",
        Host = string.Format("{0}.blob.core.windows.net", _blobServiceclient.AccountName),
        Path = string.Format("{0}/{1}", containerName, filename),
        Query = sasToken.ToString()
    };

    return fullUri.ToString();
}



public async Task<Document> GetInvoice(byte[] invoiceContent, string invoiceFilename)
{
    string filePath = await GetLinkForFile(invoiceFilename);
    UploadFile(invoiceFilename, file);
    
    return new Document()
    {           
        Url = filePath
    };  
}

The method GetInvoice is called by REST and the response (containing the URL) returned to the browser where it is opened.