run-llama/llama_index · error · ValueError

Expected 'vector_index' to be an instance of VectorStoreInde

Error message

Expected 'vector_index' to be an instance of VectorStoreIndex, got {type(value)}

What it means

Error "Expected 'vector_index' to be an instance of VectorStoreIndex, got {type(value)}" thrown in run-llama/llama_index.

Source

Thrown at llama-index-core/llama_index/core/memory/vector_memory.py:84

    # If this is on, then any message that's not a user message will be combined with the last user message
    # in the vector store.
    batch_by_user_message: bool = True

    cur_batch_textnode: TextNode = Field(
        default_factory=_get_starter_node_for_new_batch,
        description="The super node for the current active user-message batch.",
    )

    @field_validator("vector_index")
    @classmethod
    def validate_vector_index(cls, value: Any) -> Any:
        """Validate vector index."""
        # NOTE: we can't import VectorStoreIndex directly due to circular imports,
        # which is why the type is Any
        from llama_index.core.indices.vector_store import VectorStoreIndex

        if not isinstance(value, VectorStoreIndex):
            raise ValueError(
                f"Expected 'vector_index' to be an instance of VectorStoreIndex, got {type(value)}"
            )
        return value

    @classmethod
    def class_name(cls) -> str:
        """Get class name."""
        return "VectorMemory"

    @classmethod
    def from_defaults(
        cls,
        vector_store: Optional[BasePydanticVectorStore] = None,
        embed_model: Optional[EmbedType] = None,
        index_kwargs: Optional[Dict] = None,
        retriever_kwargs: Optional[Dict] = None,
        **kwargs: Any,
    ) -> "VectorMemory":

View on GitHub (pinned to afd0fef371)

Solutions

1. Pass a VectorStoreIndex instance as vector_index.
2. Build a VectorStoreIndex from your nodes first and pass it to VectorMemory.

When it happens

Trigger: Thrown at llama-index-core/llama_index/core/memory/vector_memory.py:84 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of run-llama/llama_index@afd0fef371 (2026-08-15). Data as JSON: /api/errors/7941e5334c4d3db5. Report an issue: GitHub.