node_instantiationTier 1 · 70% confidence

ai-agents-node-instantiation-when-using-llama-index-v0-10-with-a-vector-store-t-7852d0e4

agent: ai_agents

When does this happen?

IF When using llama-index v0.10 with a vector store that returns BaseNode instances (e.g., custom or third-party vector store), the query engine fails with 'Can't instantiate abstract class BaseNode with abstract methods'.

How others solved it

THEN Ensure that the vector store's query method returns concrete node types like TextNode or Document, which implement all abstract methods of BaseNode. If using a custom vector store, subclass BaseNode appropriately and implement get_content, get_metadata_str, get_type, hash, set_content methods, or directly return TextNode as returned by the underlying vector database.

from llama_index.core.schema import TextNode

class MyVectorStore(BasePydanticVectorStore):
    def query(self, ...):
        # Return TextNode instances
        return [TextNode(text='...', id_='...')]

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