microsoft/semantic-kernel · error · VectorStoreOperationException

Failed to list collection names.

Error message

Failed to list collection names.

What it means

Raised by the NoSQL store's list_collection_names when enumerating containers via database.list_containers() fails for any reason. The broad except Exception wraps the original error. This is a VectorStoreOperationException surfaced as a metadata/management failure rather than a data failure.

Source

Thrown at python/semantic_kernel/connectors/azure_cosmos_db.py:1137

            embedding_generator=embedding_generator or self.embedding_generator,
            url=str(self.cosmos_db_nosql_settings.url),
            key=self.cosmos_db_nosql_settings.key.get_secret_value() if self.cosmos_db_nosql_settings.key else None,
            cosmos_client=self.cosmos_client,
            partition_key=None,
            create_database=self.create_database,
            env_file_path=None,
            env_file_encoding=None,
            **kwargs,
        )

    @override
    async def list_collection_names(self, **kwargs) -> Sequence[str]:
        try:
            database = await self._get_database_proxy()
            containers = database.list_containers()
            return [container["id"] async for container in containers]
        except Exception as e:
            raise VectorStoreOperationException("Failed to list collection names.") from e

    @override
    async def __aexit__(self, exc_type, exc_value, traceback) -> None:
        """Exit the context manager."""
        if self.managed_client:
            await self.cosmos_client.close()

View on GitHub (pinned to c028a0c7dc)

Solutions

1. Inspect exc.__cause__ for the underlying error and status code.
2. Verify the database name and endpoint in the store settings and that the identity/key has database-read permission.
3. Ensure the cosmos client is connected (or that managed_client is True) before listing collections.

Example fix

// before
names = await store.list_collection_names()  # opaque 'Failed to list collection names.'
// after
try:
    names = await store.list_collection_names()
except VectorStoreOperationException as e:
    logger.error("list failed: %s", e.__cause__)
    names = []

from semantic_kernel.exceptions import VectorStoreOperationException

try:
    names = await store.list_collection_names()
except VectorStoreOperationException as e:
    logger.error("list_collection_names failed: %s", e.__cause__)
    names = []

When it happens

Trigger: Calling list_collection_names while the database proxy cannot be reached, the database does not exist, credentials are invalid, the SDK client is not connected, or a service/network error occurs during the async iteration.

Common situations: Wrong database name in settings; missing 'read database' permission; the managed cosmos_client was never initialized; or transient connectivity issues to the Cosmos endpoint.

Related errors

• Container could not be deleted.
• Failed to search the collection.
• Failed to check if database '{self.database_name}' exists, w
• Failed to get database proxy for '{id}'.
• Failed to get container proxy for '{container_name}'.

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/877e4422f44fa763. Report an issue: GitHub.