microsoft/qlib · error · ValueError

The default URI is not set in qlib.config.C

Error message

The default URI is not set in qlib.config.C

What it means

ExpManager.default_uri reads C['exp_manager']['kwargs']['uri'] from qlib's global config and raises this ValueError when either 'kwargs' or 'uri' is absent. Without a URI there is no tracking store, so the manager refuses to proceed rather than silently defaulting.

Source

Thrown at qlib/workflow/expm.py:288

        """
        Delete an experiment.

        Parameters
        ----------
        experiment_id  : str
            the experiment id.
        experiment_name  : str
            the experiment name.
        """
        raise NotImplementedError(f"Please implement the `delete_exp` method.")

    @property
    def default_uri(self):
        """
        Get the default tracking URI from qlib.config.C
        """
        if "kwargs" not in C.exp_manager or "uri" not in C.exp_manager["kwargs"]:
            raise ValueError("The default URI is not set in qlib.config.C")
        return C.exp_manager["kwargs"]["uri"]

    @default_uri.setter
    def default_uri(self, value):
        C.exp_manager.setdefault("kwargs", {})["uri"] = value

    @property
    def uri(self):
        """
        Get the default tracking URI or current URI.

        Returns
        -------
        The tracking URI string.
        """
        return self._active_exp_uri or self.default_uri

    def list_experiments(self):

View on GitHub (pinned to 79633dd950)

Solutions

1. Call qlib.init() (or qlib.init(exp_manager={'class': 'MLflowExpManager', 'kwargs': {'uri': 'file:./mlruns'}})) before any R usage.
2. Set the URI explicitly: R.set_exp_uri('file:./mlruns') or the default_uri setter, which writes C.exp_manager['kwargs']['uri'].
3. Inspect qlib.config.C['exp_manager'] and repair the structure if a custom config replaced it.

Example fix

# before
from qlib.workflow import R  # qlib.init() never called
R.get_uri()  # ValueError: default URI not set

# after
import qlib
qlib.init()
R.get_uri()  # 'file:.../mlruns'

from qlib.config import C
assert C.get('exp_manager', {}).get('kwargs', {}).get('uri'), 'run qlib.init() or set C.exp_manager["kwargs"]["uri"] first'
uri = R.get_uri()

try:
    uri = R.get_uri()
except ValueError:
    qlib.init()  # ensure default manager + uri exist
    uri = R.get_uri()

When it happens

Trigger: Calling R.get_uri() or any experiment API before qlib.init(); overwriting C['exp_manager'] with a dict lacking kwargs.uri (e.g. C.exp_manager = {'class': 'MLflowExpManager'}); malformed YAML config passed to qrun/qlib.init missing the uri field.

Common situations: Forgetting qlib.init() in a notebook cell before using R; custom config dicts that drop the 'kwargs' level; code that mutates C.exp_manager directly instead of using set_exp_uri/default_uri setter.

Related errors

• inner_order_indicators is necessary in un-atomic executor
• This type of input {rtype} is not supported
• Get Unexpected arguments {kwargs}
• weight_position is {}, weight_position is not in the range o
• {limit[0]} is not supported

AI-assisted analysis of microsoft/qlib@79633dd950 (2026-08-15). Data as JSON: /api/errors/c85b12736b11dcff. Report an issue: GitHub.