Python 3.9 error during SDK import

[MarkIngramUK]

When attempting to import (from label_studio_sdk import Client) the SDK in Python 3.9.6 (macOS 15.7.2) I get the following error:

TypeError: unsupported operand type(s) for |: 'type' and 'NoneType'

File "/Users/x/Code/y/venv/lib/python3.9/site-packages/label_studio_sdk/__init__.py", line 259, in <module>
    from .client import AsyncLabelStudio, LabelStudio
File "/Users/x/Code/y/venv/lib/python3.9/site-packages/label_studio_sdk/client.py", line 3, in <module>
    from .projects.client_ext import ProjectsClientExt, AsyncProjectsClientExt
File "/Users/x/Code/y/venv/lib/python3.9/site-packages/label_studio_sdk/projects/client_ext.py", line 7, in <module>
    from label_studio_sdk.label_interface import LabelInterface
File "/Users/x/Code/y/venv/lib/python3.9/site-packages/label_studio_sdk/label_interface/__init__.py", line 1, in <module>
    from .interface import LabelInterface
File "/Users/x/Code/y/venv/lib/python3.9/site-packages/label_studio_sdk/label_interface/interface.py", line 29, in <module>
    from .control_tags import (
File "/Users/x/Code/y/venv/lib/python3.9/site-packages/label_studio_sdk/label_interface/control_tags.py", line 1107, in <module>
    class CustomInterfaceTag(ControlTag):
File "/Users/x/Code/y/venv/lib/python3.9/site-packages/label_studio_sdk/label_interface/control_tags.py", line 1164, in CustomInterfaceTag
    def _try_parse_json(self, outputs_str: str) -> dict | None:

Package info:

Name: label-studio-sdk
Version: 2.0.16
Summary: 
Home-page: 
Author: 
Author-email: 
License: 
Location: /Users/x/Code/y/venv/lib/python3.9/site-packages
Requires: typing_extensions, appdirs, pydantic, ijson, requests, opencv-python-headless, urllib3, jsonschema, numpy, httpx, lxml, pydantic-core, requests-mock, xmljson, nltk, datamodel-code-generator, pandas, pyjwt, Pillow, jsf, ujson
Required-by: 

Unfortunately union syntax (dict | None) requires Python 3.10+.

[heidi-humansignal]

Hello,

Thank you for contacting Label Studio,
Looking at the traceback, the error is caused by the SDK using the newer Python union type syntax (dict | None), which is only supported starting in Python 3.10. Since you're currently running Python 3.9.6, this results in the TypeError: unsupported operand type(s) for | message you’re seeing when importing the SDK.

To resolve this, we recommend upgrading your Python environment to Python 3.10 or higher and reinstalling the SDK.
Please let us know if the above recommendations has resolved the issue.

Best Regards!

Comment by Oussama Assili
Workflow Run

[MarkIngramUK]

@heidi-humansignal , from https://labelstud.io/guide/install_requirements

To install Label Studio with pip and a virtual environment, you need Python version 3.8 or later. Run the following:

Your own docs suggest you support Python 3.8 or above.

[heidi-humansignal]

Hello Mark,

You are right that our main Label Studio server application supports Python 3.8 and above. However, the issue is specifically with the label-studio-sdk package (the Python client library), which recently introduced syntax based on PEP 604 union types (dict | None). Unfortunately, that syntax is only supported starting in Python 3.10, so SDK versions 2.0.0+ are not compatible with Python 3.8 or 3.9 even though the server is.

For now, we believe upgrading your environment to Python 3.10 or newer will resolve the import error. Could you please try it out and let me know!
Best Regards!

Comment by Oussama Assili
Workflow Run