langchain-ai/deepagents · error · ValueError

Profile key {key!r} has an empty provider or model half; exp

Error message

Profile key {key!r} has an empty provider or model half; expected 'provider:model'.

What it means

For 'provider:model' keys, both halves must be non-empty. validate_profile_key raises when partition(':') yields an empty provider or model, e.g. ':model' or 'provider:'.

Source

Thrown at libs/deepagents/deepagents/profiles/_keys.py:39

    Raises:
        ValueError: If `key` is empty, contains leading/trailing whitespace,
            has more than one `:`, has whitespace adjacent to `:`, or has
            an empty half on either side of `:`.
    """
    if not key:
        msg = "Profile key must be a non-empty string."
        raise ValueError(msg)
    if key != key.strip():
        msg = f"Profile key {key!r} has leading or trailing whitespace; expected 'provider' or 'provider:model'."
        raise ValueError(msg)
    if key.count(":") > 1:
        msg = f"Profile key {key!r} has more than one ':'; expected 'provider' or 'provider:model'."
        raise ValueError(msg)
    if ":" in key:
        provider, _, model = key.partition(":")
        if not provider or not model:
            msg = f"Profile key {key!r} has an empty provider or model half; expected 'provider:model'."
            raise ValueError(msg)
        if provider != provider.strip() or model != model.strip():
            msg = f"Profile key {key!r} has whitespace adjacent to ':'; expected 'provider:model' with no spaces around ':'."
            raise ValueError(msg)

View on GitHub (pinned to a1af029e6e)

Solutions

Provide both a non-empty provider and a non-empty model.
Omit the ':' entirely if no model is needed (use plain 'provider').
Guard against empty variables before building the key.

Example fix

// before
key = f"{provider}:"  # provider may be empty
// after
key = f"{provider}:{model}" if provider and model else provider

Defensive patterns

Strategy: validation

Validate before calling

provider, sep, model = key.partition(":")
if sep and (not provider or not model):
    raise ValueError(f"profile key {key!r} needs both provider and model")

Try / catch

try:
    register_provider_profile(key)
except ValueError as e:
    if "empty provider or model half" in str(e):
        logging.error("fix key: %s", e)
    else:
        raise

Prevention

Build keys from checked variables; omit ':' when model is absent
Add unit tests for key construction helpers

When it happens

Trigger: Registering with ':gpt-4', 'anthropic:', or ':' — typically a variable holding one half was empty.

Common situations: String formatting with an unset provider or model variable; config where the model line is blank but the colon separator remains.

Related errors

AI-assisted analysis of langchain-ai/deepagents@a1af029e6e (2026-08-29). Data as JSON: /api/errors/40a9318d39b3149f. Report an issue: GitHub.