Signature did not match in 12.30.0

[stefanbie1]

• Package Name: azure-storage-blob
• Package Version: 12.30.0
• Operating System: Ubuntu
• Python Version: 3.10.12

Describe the bug

I run this code:

from azure.storage.blob import BlobServiceClient
class Azure_blob_storage():

    def __init__(self, token) -> None:
        self.container = f"."
        self.blob_service_client = BlobServiceClient(
            account_url=token)

    def upload_file(self, source, target):
        blob_client = self.blob_service_client.get_blob_client(
            container=self.container, blob=target)
        try:
            with open(source, "rb") as data:
                blob_client.upload_blob(data)
        except Exception as err:
            print(f"File was not uploaded to blob storage\n{err.args}")

When I went from 12.29.0 to 12.30.0 I started to get this error when uploading a file:
'Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature.\nRequestId:xxx\nTime:2026-06-11T11:18:05.9133423Z\nErrorCode:AuthenticationFailed\nauthenticationerrordetail:Signature did not match. String to sign used was \n\n\n/blob/rdswflogsprod/SPA3_INT/HPA_2/DOS_6_0/pre_flash\nread_write_2026-12-31\n\nhttps\n2023-08-03\nd\n\n\n\n\n\n\n',

Going back to 12.29.0 it works fine again

Do you know what could be the issue here?

[kashifkhan]

Thank you for the feedback @stefanbie1. Ill route this to the right folks who can help you further

[github-actions]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @jalauzon-msft @vincenttran-msft.

[weirongw23-msft]

Hey @stefanbie1, thanks for the context and feedback here. Based on our validation and setup, setting a container with a . name is not possible. According the Azure Blob Service Docs, the container names must not have any . in it, and any names shorter than 3 characters are not possible, so container names like ., .., and co.ntainer are not accepted. Please refer to the documentation for what's forms a valid container name.

However, one thing that could help us is the version of the SDK (exact service version along with the version of azure-storage-blob) where this was working, so we can validate our repros. One way to do this is to give us a sample output of the logs. Thanks so much.